diff --git a/dom/bindings/Bindings.conf b/dom/bindings/Bindings.conf
index 086accbe59f6..342502498f91 100644
--- a/dom/bindings/Bindings.conf
+++ b/dom/bindings/Bindings.conf
@@ -413,6 +413,11 @@ DOMInterfaces = {
     'headerFile': 'IDBEvents.h',
 },
 
+'IOUtils': {
+    'nativeType': 'mozilla::IOUtils',
+    'headerFile': 'mozilla/IOUtils.h',
+},
+
 'InspectorFontFace': {
     'wrapperCache': False,
 },
@@ -589,6 +594,11 @@ DOMInterfaces = {
     'headerFile': 'CanvasPath.h'
 },
 
+'PathUtils': {
+    'nativeType': 'mozilla::PathUtils',
+    'headerFile': 'mozilla/PathUtils.h',
+},
+
 'Performance' : {
     'implicitJSContext': [
         'mark'
@@ -858,7 +868,8 @@ DOMInterfaces = {
 },
 
 'SyncReadFile': {
-    'headerFile': 'mozilla/dom/IOUtils.h',
+    'nativeType': 'mozilla::SyncReadFile',
+    'headerFile': 'mozilla/IOUtils.h',
 },
 
 'Text': {
diff --git a/dom/system/moz.build b/dom/system/moz.build
index fa7367fd65d6..73e77871371e 100644
--- a/dom/system/moz.build
+++ b/dom/system/moz.build
@@ -14,12 +14,6 @@ with Files("*ocationProvider*"):
 with Files("windows/*LocationProvider*"):
     BUG_COMPONENT = ("Core", "DOM: Geolocation")
 
-with Files("IOUtils*"):
-    BUG_COMPONENT = ("Toolkit", "IOUtils and PathUtils")
-
-with Files("PathUtils*"):
-    BUG_COMPONENT = ("Toolkit", "IOUtils and PathUtils")
-
 with Files("mac/*LocationProvider*"):
     BUG_COMPONENT = ("Core", "DOM: Geolocation")
 
@@ -32,21 +26,9 @@ with Files("linux/*LocationProvider*"):
 with Files("android/*LocationProvider*"):
     BUG_COMPONENT = ("Core", "DOM: Geolocation")
 
-with Files("tests/chrome.toml"):
-    BUG_COMPONENT = ("Toolkit", "IOUtils and PathUtils")
-
-with Files("tests/*constants*"):
-    BUG_COMPONENT = ("Toolkit", "IOUtils and PathUtils")
-
-with Files("tests/ioutils/**"):
-    BUG_COMPONENT = ("Toolkit", "IOUtils and PathUtils")
-
 with Files("tests/mochitest.toml"):
     BUG_COMPONENT = ("Core", "DOM: Device Interfaces")
 
-with Files("test/*pathutils*"):
-    BUG_COMPONENT = ("Toolkit", "IOUtils and PathUtils")
-
 with Files("tests/*1197901*"):
     BUG_COMPONENT = ("Core", "DOM: Device Interfaces")
 
@@ -78,17 +60,10 @@ EXPORTS += [
     "nsOSPermissionRequestBase.h",
 ]
 
-EXPORTS.mozilla.dom += [
-    "IOUtils.h",
-    "PathUtils.h",
-]
-
 UNIFIED_SOURCES += [
-    "IOUtils.cpp",
     "nsDeviceSensors.cpp",
     "nsHapticFeedback.cpp",
     "nsOSPermissionRequestBase.cpp",
-    "PathUtils.cpp",
 ]
 
 EXTRA_JS_MODULES += [
@@ -110,5 +85,4 @@ LOCAL_INCLUDES += [
     "/xpcom/base",
 ]
 
-MOCHITEST_CHROME_MANIFESTS += ["tests/chrome.toml", "tests/ioutils/chrome.toml"]
 MOCHITEST_MANIFESTS += ["tests/mochitest.toml"]
diff --git a/dom/system/tests/chrome.toml b/dom/system/tests/chrome.toml
deleted file mode 100644
index 87f782b4659f..000000000000
--- a/dom/system/tests/chrome.toml
+++ /dev/null
@@ -1,6 +0,0 @@
-[DEFAULT]
-
-["test_pathutils.html"]
-
-["test_pathutils_worker.xhtml"]
-support-files = ["pathutils_worker.js"]
diff --git a/mots.yaml b/mots.yaml
index 5b5478649306..42a5b1fe86f9 100644
--- a/mots.yaml
+++ b/mots.yaml
@@ -8,7 +8,7 @@
 # documentation and how to modify this file.
 repo: mozilla-central
 created_at: '2021-10-14T12:50:40.073465'
-updated_at: '2025-04-01T14:21:39.951774+00:00'
+updated_at: '2025-04-02T20:26:15.852994+00:00'
 export:
   path: ./docs/mots/index.rst
   format: rst
@@ -3245,6 +3245,8 @@ modules:
   - name: 'Core: XPCOM'
     description: The cross-platform object model and core data structures.
     includes:
+      - dom/chrome-webidl/IOUtils.webidl
+      - dom/chrome-webidl/PathUtils.webidl
       - startupcache/**/*
       - xpcom/**/*
       - xpcom/base/**/*
@@ -3253,6 +3255,8 @@ modules:
       - xpcom/docs/**/*
       - xpcom/ds/**/*
       - xpcom/glue/**/*
+      - xpcom/io/**/*
+      - xpcom/ioutils/**/*
       - xpcom/reflect/**/*
       - xpcom/rust/**/*
       - xpcom/system/**/*
@@ -3271,6 +3275,7 @@ modules:
       url: :ref:`XPCOM`
       components:
         - Core::XPCOM
+        - Toolkit::IOUtils and PathUtils
       review_group: xpcom-reviewers
     owners:
       - *nika
@@ -4541,5 +4546,5 @@ modules:
         - Ryan Tilder
       group: dev-platform
 hashes:
-  config: 1f1a65ce9444d293f1f1b8fc74b954bea0aa5a27
-  export: 26b31fcb1ebef52108b7df136973ebf35a4ddc5b
+  config: 93b411d8790c372028509fc186c01b8a34ec8cd5
+  export: 3823627c4a11aab9dc12d92537080eeddffceb34
diff --git a/toolkit/components/terminator/nsTerminator.cpp b/toolkit/components/terminator/nsTerminator.cpp
index 00557ad9e2de..e613f0b27b69 100644
--- a/toolkit/components/terminator/nsTerminator.cpp
+++ b/toolkit/components/terminator/nsTerminator.cpp
@@ -49,7 +49,6 @@
 #include "mozilla/Unused.h"
 #include "mozilla/Telemetry.h"
 
-#include "mozilla/dom/IOUtils.h"
 #include "mozilla/dom/workerinternals/RuntimeService.h"
 
 // Normally, the number of milliseconds that AsyncShutdown waits until
diff --git a/dom/system/IOUtils.cpp b/xpcom/ioutils/IOUtils.cpp
similarity index 99%
rename from dom/system/IOUtils.cpp
rename to xpcom/ioutils/IOUtils.cpp
index 6688ccbe2a4c..103c8ef77698 100644
--- a/dom/system/IOUtils.cpp
+++ b/xpcom/ioutils/IOUtils.cpp
@@ -9,7 +9,6 @@
 #include <cstdint>
 
 #include "ErrorList.h"
-#include "TypedArray.h"
 #include "js/ArrayBuffer.h"
 #include "js/ColumnNumber.h"  // JS::ColumnNumberOneOrigin
 #include "js/JSON.h"
@@ -96,10 +95,13 @@
     }                                                         \
   } while (0)
 
+
+using namespace mozilla::dom;
+
 static constexpr auto SHUTDOWN_ERROR =
     "IOUtils: Shutting down and refusing additional I/O tasks"_ns;
 
-namespace mozilla::dom {
+namespace mozilla {
 
 // static helper functions
 
@@ -158,7 +160,7 @@ static nsCString FormatErrorMessage(nsresult aError,
 [[nodiscard]] inline bool ToJSValue(
     JSContext* aCx, const IOUtils::InternalFileInfo& aInternalFileInfo,
     JS::MutableHandle<JS::Value> aValue) {
-  FileInfo info;
+  dom::FileInfo info;
   info.mPath.Construct(aInternalFileInfo.mPath);
   info.mType.Construct(aInternalFileInfo.mType);
   info.mSize.Construct(aInternalFileInfo.mSize);
@@ -331,8 +333,8 @@ void IOUtils::DispatchAndResolve(IOUtils::EventQueue* aQueue, Promise* aPromise,
   if (!NS_IsMainThread()) {
     // We need to manually keep the worker alive until the promise returned by
     // Dispatch() resolves or rejects.
-    workerRef = StrongWorkerRef::CreateForcibly(GetCurrentThreadWorkerPrivate(),
-                                                __func__);
+    workerRef = StrongWorkerRef::CreateForcibly(
+        GetCurrentThreadWorkerPrivate(), __func__);
   }
 
   if (RefPtr<IOPromise<OkT>> p = aQueue->Dispatch<OkT, Fn>(std::move(aFunc))) {
@@ -1884,16 +1886,16 @@ Result<IOUtils::InternalFileInfo, IOUtils::IOError> IOUtils::StatSync(
   }
 
   // Now we can populate the info object by querying the file.
-  info.mType = FileType::Regular;
+  info.mType = dom::FileType::Regular;
   if (!isRegular) {
     bool isDir = false;
     IOUTILS_TRY_WITH_CONTEXT(aFile->IsDirectory(&isDir), "Could not stat `%s'",
                              aFile->HumanReadablePath().get());
-    info.mType = isDir ? FileType::Directory : FileType::Other;
+    info.mType = isDir ? dom::FileType::Directory : dom::FileType::Other;
   }
 
   int64_t size = -1;
-  if (info.mType == FileType::Regular) {
+  if (info.mType == dom::FileType::Regular) {
     IOUTILS_TRY_WITH_CONTEXT(aFile->GetFileSize(&size), "Could not stat `%s'",
                              aFile->HumanReadablePath().get());
   }
@@ -2099,6 +2101,8 @@ Result<nsString, IOUtils::IOError> IOUtils::CreateUniqueSync(
 /* static */
 Result<nsCString, IOUtils::IOError> IOUtils::ComputeHexDigestSync(
     nsIFile* aFile, const HashAlgorithm aAlgorithm) {
+  using HashAlgorithm = HashAlgorithm;
+
   static constexpr size_t BUFFER_SIZE = 8192;
 
   SECOidTag alg;
@@ -3093,7 +3097,7 @@ uint32_t IOUtils::LaunchProcess(GlobalObject& aGlobal,
 }
 #endif  // XP_UNIX
 
-}  // namespace mozilla::dom
+}  // namespace mozilla
 
 #undef REJECT_IF_INIT_PATH_FAILED
 #undef IOUTILS_TRY_WITH_CONTEXT
diff --git a/dom/system/IOUtils.h b/xpcom/ioutils/IOUtils.h
similarity index 76%
rename from dom/system/IOUtils.h
rename to xpcom/ioutils/IOUtils.h
index 19800e392955..8d44d74761ba 100644
--- a/dom/system/IOUtils.h
+++ b/xpcom/ioutils/IOUtils.h
@@ -51,8 +51,6 @@ class PR_CloseDelete {
   void operator()(PRFileDesc* aPtr) const { PR_Close(aPtr); }
 };
 
-namespace dom {
-
 /**
  * Implementation for the Web IDL interface at dom/chrome-webidl/IOUtils.webidl.
  * Methods of this class must only be called from the parent process.
@@ -72,71 +70,67 @@ class IOUtils final {
   using PhaseArray = EnumeratedArray<IOUtils::ShutdownPhase, T,
                                      size_t(IOUtils::ShutdownPhase::Count)>;
 
-  static already_AddRefed<Promise> Read(GlobalObject& aGlobal,
-                                        const nsAString& aPath,
-                                        const ReadOptions& aOptions,
-                                        ErrorResult& aError);
+  static already_AddRefed<dom::Promise> Read(dom::GlobalObject& aGlobal,
 
-  static already_AddRefed<Promise> ReadUTF8(GlobalObject& aGlobal,
-                                            const nsAString& aPath,
-                                            const ReadUTF8Options& aOptions,
-                                            ErrorResult& aError);
-
-  static already_AddRefed<Promise> ReadJSON(GlobalObject& aGlobal,
-                                            const nsAString& aPath,
-                                            const ReadUTF8Options& aOptions,
-                                            ErrorResult& aError);
-
-  static already_AddRefed<Promise> Write(GlobalObject& aGlobal,
-                                         const nsAString& aPath,
-                                         const Uint8Array& aData,
-                                         const WriteOptions& aOptions,
-                                         ErrorResult& aError);
-
-  static already_AddRefed<Promise> WriteUTF8(GlobalObject& aGlobal,
                                              const nsAString& aPath,
-                                             const nsACString& aString,
-                                             const WriteOptions& aOptions,
+                                             const dom::ReadOptions& aOptions,
                                              ErrorResult& aError);
 
-  static already_AddRefed<Promise> WriteJSON(GlobalObject& aGlobal,
-                                             const nsAString& aPath,
-                                             JS::Handle<JS::Value> aValue,
-                                             const WriteOptions& aOptions,
+  static already_AddRefed<dom::Promise> ReadUTF8(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::ReadUTF8Options& aOptions, ErrorResult& aError);
+
+  static already_AddRefed<dom::Promise> ReadJSON(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::ReadUTF8Options& aOptions, ErrorResult& aError);
+
+  static already_AddRefed<dom::Promise> Write(dom::GlobalObject& aGlobal,
+                                              const nsAString& aPath,
+                                              const dom::Uint8Array& aData,
+                                              const dom::WriteOptions& aOptions,
+                                              ErrorResult& aError);
+
+  static already_AddRefed<dom::Promise> WriteUTF8(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const nsACString& aString, const dom::WriteOptions& aOptions,
+      ErrorResult& aError);
+
+  static already_AddRefed<dom::Promise> WriteJSON(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      JS::Handle<JS::Value> aValue, const dom::WriteOptions& aOptions,
+      ErrorResult& aError);
+
+  static already_AddRefed<dom::Promise> Move(dom::GlobalObject& aGlobal,
+                                             const nsAString& aSourcePath,
+                                             const nsAString& aDestPath,
+                                             const dom::MoveOptions& aOptions,
                                              ErrorResult& aError);
 
-  static already_AddRefed<Promise> Move(GlobalObject& aGlobal,
-                                        const nsAString& aSourcePath,
-                                        const nsAString& aDestPath,
-                                        const MoveOptions& aOptions,
-                                        ErrorResult& aError);
+  static already_AddRefed<dom::Promise> Remove(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::RemoveOptions& aOptions, ErrorResult& aError);
 
-  static already_AddRefed<Promise> Remove(GlobalObject& aGlobal,
-                                          const nsAString& aPath,
-                                          const RemoveOptions& aOptions,
-                                          ErrorResult& aError);
+  static already_AddRefed<dom::Promise> MakeDirectory(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::MakeDirectoryOptions& aOptions, ErrorResult& aError);
 
-  static already_AddRefed<Promise> MakeDirectory(
-      GlobalObject& aGlobal, const nsAString& aPath,
-      const MakeDirectoryOptions& aOptions, ErrorResult& aError);
+  static already_AddRefed<dom::Promise> Stat(dom::GlobalObject& aGlobal,
+                                             const nsAString& aPath,
+                                             ErrorResult& aError);
 
-  static already_AddRefed<Promise> Stat(GlobalObject& aGlobal,
-                                        const nsAString& aPath,
-                                        ErrorResult& aError);
+  static already_AddRefed<dom::Promise> Copy(dom::GlobalObject& aGlobal,
+                                             const nsAString& aSourcePath,
+                                             const nsAString& aDestPath,
+                                             const dom::CopyOptions& aOptions,
+                                             ErrorResult& aError);
 
-  static already_AddRefed<Promise> Copy(GlobalObject& aGlobal,
-                                        const nsAString& aSourcePath,
-                                        const nsAString& aDestPath,
-                                        const CopyOptions& aOptions,
-                                        ErrorResult& aError);
+  static already_AddRefed<dom::Promise> SetAccessTime(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::Optional<int64_t>& aAccess, ErrorResult& aError);
 
-  static already_AddRefed<Promise> SetAccessTime(
-      GlobalObject& aGlobal, const nsAString& aPath,
-      const Optional<int64_t>& aAccess, ErrorResult& aError);
-
-  static already_AddRefed<Promise> SetModificationTime(
-      GlobalObject& aGlobal, const nsAString& aPath,
-      const Optional<int64_t>& aModification, ErrorResult& aError);
+  static already_AddRefed<dom::Promise> SetModificationTime(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::Optional<int64_t>& aModification, ErrorResult& aError);
 
  private:
   using SetTimeFn = decltype(&nsIFile::SetLastAccessedTime);
@@ -144,109 +138,101 @@ class IOUtils final {
   static_assert(
       std::is_same_v<SetTimeFn, decltype(&nsIFile::SetLastModifiedTime)>);
 
-  static already_AddRefed<Promise> SetTime(GlobalObject& aGlobal,
-                                           const nsAString& aPath,
-                                           const Optional<int64_t>& aNewTime,
-                                           SetTimeFn aSetTimeFn,
-                                           const char* const aTimeKind,
-                                           ErrorResult& aError);
+  static already_AddRefed<dom::Promise> SetTime(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::Optional<int64_t>& aNewTime, SetTimeFn aSetTimeFn,
+      const char* const aTimeKind, ErrorResult& aError);
 
  public:
-  static already_AddRefed<Promise> HasChildren(
-      GlobalObject& aGlobal, const nsAString& aPath,
-      const HasChildrenOptions& aOptions, ErrorResult& aError);
+  static already_AddRefed<dom::Promise> HasChildren(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::HasChildrenOptions& aOptions, ErrorResult& aError);
 
-  static already_AddRefed<Promise> GetChildren(
-      GlobalObject& aGlobal, const nsAString& aPath,
-      const GetChildrenOptions& aOptions, ErrorResult& aError);
+  static already_AddRefed<dom::Promise> GetChildren(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::GetChildrenOptions& aOptions, ErrorResult& aError);
 
-  static already_AddRefed<Promise> SetPermissions(GlobalObject& aGlobal,
-                                                  const nsAString& aPath,
-                                                  uint32_t aPermissions,
-                                                  const bool aHonorUmask,
-                                                  ErrorResult& aError);
+  static already_AddRefed<dom::Promise> SetPermissions(
+      dom::GlobalObject& aGlobal, const nsAString& aPath, uint32_t aPermissions,
+      const bool aHonorUmask, ErrorResult& aError);
 
-  static already_AddRefed<Promise> Exists(GlobalObject& aGlobal,
-                                          const nsAString& aPath,
-                                          ErrorResult& aError);
+  static already_AddRefed<dom::Promise> Exists(dom::GlobalObject& aGlobal,
+                                               const nsAString& aPath,
+                                               ErrorResult& aError);
 
-  static already_AddRefed<Promise> CreateUniqueFile(GlobalObject& aGlobal,
-                                                    const nsAString& aParent,
-                                                    const nsAString& aPrefix,
-                                                    const uint32_t aPermissions,
-                                                    ErrorResult& aError);
-  static already_AddRefed<Promise> CreateUniqueDirectory(
-      GlobalObject& aGlobal, const nsAString& aParent, const nsAString& aPrefix,
-      const uint32_t aPermissions, ErrorResult& aError);
+  static already_AddRefed<dom::Promise> CreateUniqueFile(
+      dom::GlobalObject& aGlobal, const nsAString& aParent,
+      const nsAString& aPrefix, const uint32_t aPermissions,
+      ErrorResult& aError);
+  static already_AddRefed<dom::Promise> CreateUniqueDirectory(
+      dom::GlobalObject& aGlobal, const nsAString& aParent,
+      const nsAString& aPrefix, const uint32_t aPermissions,
+      ErrorResult& aError);
 
  private:
   /**
    * A helper method for CreateUniqueFile and CreateUniqueDirectory.
    */
-  static already_AddRefed<Promise> CreateUnique(GlobalObject& aGlobal,
-                                                const nsAString& aParent,
-                                                const nsAString& aPrefix,
-                                                const uint32_t aFileType,
-                                                const uint32_t aPermissions,
-                                                ErrorResult& aError);
+  static already_AddRefed<dom::Promise> CreateUnique(
+      dom::GlobalObject& aGlobal, const nsAString& aParent,
+      const nsAString& aPrefix, const uint32_t aFileType,
+      const uint32_t aPermissions, ErrorResult& aError);
 
  public:
-  static already_AddRefed<Promise> ComputeHexDigest(
-      GlobalObject& aGlobal, const nsAString& aPath,
-      const HashAlgorithm aAlgorithm, ErrorResult& aError);
+  static already_AddRefed<dom::Promise> ComputeHexDigest(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const dom::HashAlgorithm aAlgorithm, ErrorResult& aError);
 
 #if defined(XP_WIN)
-  static already_AddRefed<Promise> GetWindowsAttributes(GlobalObject& aGlobal,
-                                                        const nsAString& aPath,
-                                                        ErrorResult& aError);
+  static already_AddRefed<dom::Promise> GetWindowsAttributes(
+      dom::GlobalObject& aGlobal, const nsAString& aPath, ErrorResult& aError);
 
-  static already_AddRefed<Promise> SetWindowsAttributes(
-      GlobalObject& aGlobal, const nsAString& aPath,
+  static already_AddRefed<dom::Promise> SetWindowsAttributes(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
       const mozilla::dom::WindowsFileAttributes& aAttrs, ErrorResult& aError);
 #elif defined(XP_MACOSX)
-  static already_AddRefed<Promise> HasMacXAttr(GlobalObject& aGlobal,
-                                               const nsAString& aPath,
-                                               const nsACString& aAttr,
-                                               ErrorResult& aError);
-  static already_AddRefed<Promise> GetMacXAttr(GlobalObject& aGlobal,
-                                               const nsAString& aPath,
-                                               const nsACString& aAttr,
-                                               ErrorResult& aError);
-  static already_AddRefed<Promise> SetMacXAttr(GlobalObject& aGlobal,
-                                               const nsAString& aPath,
-                                               const nsACString& aAttr,
-                                               const Uint8Array& aValue,
-                                               ErrorResult& aError);
-  static already_AddRefed<Promise> DelMacXAttr(GlobalObject& aGlobal,
-                                               const nsAString& aPath,
-                                               const nsACString& aAttr,
-                                               ErrorResult& aError);
+  static already_AddRefed<dom::Promise> HasMacXAttr(dom::GlobalObject& aGlobal,
+                                                    const nsAString& aPath,
+                                                    const nsACString& aAttr,
+                                                    ErrorResult& aError);
+  static already_AddRefed<dom::Promise> GetMacXAttr(dom::GlobalObject& aGlobal,
+                                                    const nsAString& aPath,
+                                                    const nsACString& aAttr,
+                                                    ErrorResult& aError);
+  static already_AddRefed<dom::Promise> SetMacXAttr(
+      dom::GlobalObject& aGlobal, const nsAString& aPath,
+      const nsACString& aAttr, const dom::Uint8Array& aValue,
+      ErrorResult& aError);
+  static already_AddRefed<dom::Promise> DelMacXAttr(dom::GlobalObject& aGlobal,
+                                                    const nsAString& aPath,
+                                                    const nsACString& aAttr,
+                                                    ErrorResult& aError);
 #endif
 
 #ifdef XP_UNIX
-  using UnixString = OwningUTF8StringOrUint8Array;
-  static uint32_t LaunchProcess(GlobalObject& aGlobal,
-                                const Sequence<UnixString>& aArgv,
-                                const LaunchOptions& aOptions,
+  using UnixString = dom::OwningUTF8StringOrUint8Array;
+  static uint32_t LaunchProcess(dom::GlobalObject& aGlobal,
+                                const dom::Sequence<UnixString>& aArgv,
+                                const dom::LaunchOptions& aOptions,
                                 ErrorResult& aRv);
 #endif
 
-  static already_AddRefed<Promise> GetFile(
-      GlobalObject& aGlobal, const Sequence<nsString>& aComponents,
+  static already_AddRefed<dom::Promise> GetFile(
+      dom::GlobalObject& aGlobal, const dom::Sequence<nsString>& aComponents,
       ErrorResult& aError);
 
-  static already_AddRefed<Promise> GetDirectory(
-      GlobalObject& aGlobal, const Sequence<nsString>& aComponents,
+  static already_AddRefed<dom::Promise> GetDirectory(
+      dom::GlobalObject& aGlobal, const dom::Sequence<nsString>& aComponents,
       ErrorResult& aError);
 
-  static void GetProfileBeforeChange(GlobalObject& aGlobal,
+  static void GetProfileBeforeChange(dom::GlobalObject& aGlobal,
                                      JS::MutableHandle<JS::Value>,
                                      ErrorResult& aRv);
 
-  static void GetSendTelemetry(GlobalObject& aGlobal,
+  static void GetSendTelemetry(dom::GlobalObject& aGlobal,
                                JS::MutableHandle<JS::Value>, ErrorResult& aRv);
 
-  static RefPtr<SyncReadFile> OpenFileForSyncReading(GlobalObject& aGlobal,
+  static RefPtr<SyncReadFile> OpenFileForSyncReading(dom::GlobalObject& aGlobal,
                                                      const nsAString& aPath,
                                                      ErrorResult& aRv);
 
@@ -255,7 +241,7 @@ class IOUtils final {
   /**
    * The kind of buffer to allocate.
    *
-   * This controls what kind of JS object (a JSString or a Uint8Array) is
+   * This controls what kind of JS object (a JSString or a dom::Uint8Array) is
    * returned by |ToJSValue()|.
    */
   enum class BufferKind {
@@ -277,9 +263,8 @@ class IOUtils final {
   class State;
 
   template <typename Fn>
-  static already_AddRefed<Promise> WithPromiseAndState(GlobalObject& aGlobal,
-                                                       ErrorResult& aError,
-                                                       Fn aFn);
+  static already_AddRefed<dom::Promise> WithPromiseAndState(
+      dom::GlobalObject& aGlobal, ErrorResult& aError, Fn aFn);
 
   /**
    * Dispatch a task on the event queue and resolve or reject the associated
@@ -293,16 +278,16 @@ class IOUtils final {
    * @param aFunc The task to run.
    */
   template <typename OkT, typename Fn>
-  static void DispatchAndResolve(EventQueue* aQueue, Promise* aPromise,
+  static void DispatchAndResolve(EventQueue* aQueue, dom::Promise* aPromise,
                                  Fn aFunc);
 
   /**
-   * Creates a new JS Promise.
+   * Creates a new JS dom::Promise.
    *
    * @return The new promise, or |nullptr| on failure.
    */
-  static already_AddRefed<Promise> CreateJSPromise(GlobalObject& aGlobal,
-                                                   ErrorResult& aError);
+  static already_AddRefed<dom::Promise> CreateJSPromise(
+      dom::GlobalObject& aGlobal, ErrorResult& aError);
 
   // Allow conversion of |InternalFileInfo| with |ToJSValue|.
   friend bool ToJSValue(JSContext* aCx,
@@ -539,7 +524,7 @@ class IOUtils final {
    * @return The hash of the file, as a hex digest.
    */
   static Result<nsCString, IOError> ComputeHexDigestSync(
-      nsIFile* aFile, const HashAlgorithm aAlgorithm);
+      nsIFile* aFile, const dom::HashAlgorithm aAlgorithm);
 
 #if defined(XP_WIN)
   /**
@@ -573,7 +558,7 @@ class IOUtils final {
                                              const nsCString& aAttr);
 #endif
 
-  static void GetShutdownClient(GlobalObject& aGlobal,
+  static void GetShutdownClient(dom::GlobalObject& aGlobal,
                                 JS::MutableHandle<JS::Value> aClient,
                                 ErrorResult& aRv, const ShutdownPhase aPhase);
 
@@ -727,7 +712,7 @@ class IOUtils::IOError {
  */
 struct IOUtils::InternalFileInfo {
   nsString mPath;
-  FileType mType = FileType::Other;
+  dom::FileType mType = dom::FileType::Other;
   uint64_t mSize = 0;
   Maybe<PRTime> mCreationTime;  // In ms since epoch.
   PRTime mLastAccessed = 0;     // In ms since epoch.
@@ -746,12 +731,12 @@ struct IOUtils::InternalFileInfo {
 struct IOUtils::InternalWriteOpts {
   RefPtr<nsIFile> mBackupFile;
   RefPtr<nsIFile> mTmpFile;
-  WriteMode mMode;
+  dom::WriteMode mMode;
   bool mFlush = false;
   bool mCompress = false;
 
   static Result<InternalWriteOpts, IOUtils::IOError> FromBinding(
-      const WriteOptions& aOptions);
+      const dom::WriteOptions& aOptions);
 };
 
 /**
@@ -938,7 +923,7 @@ class SyncReadFile : public nsISupports, public nsWrapperCache {
                                JS::Handle<JSObject*> aGivenProto) override;
 
   int64_t Size() const { return mSize; }
-  void ReadBytesInto(const Uint8Array&, const int64_t, ErrorResult& aRv);
+  void ReadBytesInto(const dom::Uint8Array&, const int64_t, ErrorResult& aRv);
   void Close();
 
  private:
@@ -949,7 +934,6 @@ class SyncReadFile : public nsISupports, public nsWrapperCache {
   int64_t mSize = 0;
 };
 
-}  // namespace dom
 }  // namespace mozilla
 
 #endif
diff --git a/dom/system/PathUtils.cpp b/xpcom/ioutils/PathUtils.cpp
similarity index 99%
rename from dom/system/PathUtils.cpp
rename to xpcom/ioutils/PathUtils.cpp
index 1d4fee8df163..258024845187 100644
--- a/dom/system/PathUtils.cpp
+++ b/xpcom/ioutils/PathUtils.cpp
@@ -31,7 +31,9 @@
 #include "nsURLHelper.h"
 #include "xpcpublic.h"
 
-namespace mozilla::dom {
+using namespace mozilla::dom;
+
+namespace mozilla {
 
 static constexpr auto ERROR_EMPTY_PATH =
     "PathUtils does not support empty paths"_ns;
@@ -632,4 +634,4 @@ nsresult PathUtils::DirectoryCache::PopulateDirectoriesImpl(
   return NS_OK;
 }
 
-}  // namespace mozilla::dom
+}  // namespace mozilla
diff --git a/dom/system/PathUtils.h b/xpcom/ioutils/PathUtils.h
similarity index 77%
rename from dom/system/PathUtils.h
rename to xpcom/ioutils/PathUtils.h
index 1870d92f2352..67f72d173e5e 100644
--- a/dom/system/PathUtils.h
+++ b/xpcom/ioutils/PathUtils.h
@@ -23,8 +23,6 @@
 namespace mozilla {
 class ErrorResult;
 
-namespace dom {
-
 class PathUtils final {
  public:
   /**
@@ -41,14 +39,15 @@ class PathUtils final {
    */
   static nsresult InitFileWithPath(nsIFile* aFile, const nsAString& aPath);
 
-  static void Filename(const GlobalObject&, const nsAString& aPath,
+  static void Filename(const dom::GlobalObject&, const nsAString& aPath,
                        nsString& aResult, ErrorResult& aErr);
 
-  static void Parent(const GlobalObject&, const nsAString& aPath,
+  static void Parent(const dom::GlobalObject&, const nsAString& aPath,
                      const int32_t aDepth, nsString& aResult,
                      ErrorResult& aErr);
 
-  static void Join(const GlobalObject&, const Sequence<nsString>& aComponents,
+  static void Join(const dom::GlobalObject&,
+                   const dom::Sequence<nsString>& aComponents,
                    nsString& aResult, ErrorResult& aErr);
 
   /**
@@ -65,45 +64,47 @@ class PathUtils final {
   static already_AddRefed<nsIFile> Join(const Span<const nsString>& aComponents,
                                         ErrorResult& aErr);
 
-  static void JoinRelative(const GlobalObject&, const nsAString& aBasePath,
+  static void JoinRelative(const dom::GlobalObject&, const nsAString& aBasePath,
                            const nsAString& aRelativePath, nsString& aResult,
                            ErrorResult& aErr);
 
-  static void ToExtendedWindowsPath(const GlobalObject&, const nsAString& aPath,
-                                    nsString& aResult, ErrorResult& aErr);
-
-  static void Normalize(const GlobalObject&, const nsAString& aPath,
-                        nsString& aResult, ErrorResult& aErr);
-
-  static void Split(const GlobalObject&, const nsAString& aPath,
-                    nsTArray<nsString>& aResult, ErrorResult& aErr);
-
-  static void SplitRelative(const GlobalObject& aGlobal, const nsAString& aPath,
-                            const SplitRelativeOptions& aOptions,
-                            nsTArray<nsString>& aResult, ErrorResult& aErr);
-
-  static void ToFileURI(const GlobalObject&, const nsAString& aPath,
-                        nsCString& aResult, ErrorResult& aErr);
-
-  static bool IsAbsolute(const GlobalObject&, const nsAString& aPath);
-
-  static void GetProfileDirSync(const GlobalObject&, nsString& aResult,
-                                ErrorResult& aErr);
-  static void GetLocalProfileDirSync(const GlobalObject&, nsString& aResult,
-                                     ErrorResult& aErr);
-  static void GetTempDirSync(const GlobalObject&, nsString& aResult,
-                             ErrorResult& aErr);
-  static void GetXulLibraryPathSync(const GlobalObject&, nsString& aResult,
+  static void ToExtendedWindowsPath(const dom::GlobalObject&,
+                                    const nsAString& aPath, nsString& aResult,
                                     ErrorResult& aErr);
 
-  static already_AddRefed<Promise> GetProfileDirAsync(
-      const GlobalObject& aGlobal, ErrorResult& aErr);
-  static already_AddRefed<Promise> GetLocalProfileDirAsync(
-      const GlobalObject& aGlobal, ErrorResult& aErr);
-  static already_AddRefed<Promise> GetTempDirAsync(const GlobalObject& aGlobal,
-                                                   ErrorResult& aErr);
-  static already_AddRefed<Promise> GetXulLibraryPathAsync(
-      const GlobalObject& aGlobal, ErrorResult& aErr);
+  static void Normalize(const dom::GlobalObject&, const nsAString& aPath,
+                        nsString& aResult, ErrorResult& aErr);
+
+  static void Split(const dom::GlobalObject&, const nsAString& aPath,
+                    nsTArray<nsString>& aResult, ErrorResult& aErr);
+
+  static void SplitRelative(const dom::GlobalObject& aGlobal,
+                            const nsAString& aPath,
+                            const dom::SplitRelativeOptions& aOptions,
+                            nsTArray<nsString>& aResult, ErrorResult& aErr);
+
+  static void ToFileURI(const dom::GlobalObject&, const nsAString& aPath,
+                        nsCString& aResult, ErrorResult& aErr);
+
+  static bool IsAbsolute(const dom::GlobalObject&, const nsAString& aPath);
+
+  static void GetProfileDirSync(const dom::GlobalObject&, nsString& aResult,
+                                ErrorResult& aErr);
+  static void GetLocalProfileDirSync(const dom::GlobalObject&,
+                                     nsString& aResult, ErrorResult& aErr);
+  static void GetTempDirSync(const dom::GlobalObject&, nsString& aResult,
+                             ErrorResult& aErr);
+  static void GetXulLibraryPathSync(const dom::GlobalObject&, nsString& aResult,
+                                    ErrorResult& aErr);
+
+  static already_AddRefed<dom::Promise> GetProfileDirAsync(
+      const dom::GlobalObject& aGlobal, ErrorResult& aErr);
+  static already_AddRefed<dom::Promise> GetLocalProfileDirAsync(
+      const dom::GlobalObject& aGlobal, ErrorResult& aErr);
+  static already_AddRefed<dom::Promise> GetTempDirAsync(
+      const dom::GlobalObject& aGlobal, ErrorResult& aErr);
+  static already_AddRefed<dom::Promise> GetXulLibraryPathAsync(
+      const dom::GlobalObject& aGlobal, ErrorResult& aErr);
 
  private:
   class DirectoryCache;
@@ -175,9 +176,9 @@ class PathUtils::DirectoryCache final {
    *
    * @return A promise that resolves to the path of the requested directory.
    */
-  already_AddRefed<Promise> GetDirectoryAsync(const GlobalObject& aGlobalObject,
-                                              ErrorResult& aErr,
-                                              const Directory aRequestedDir);
+  already_AddRefed<dom::Promise> GetDirectoryAsync(
+      const dom::GlobalObject& aGlobalObject, ErrorResult& aErr,
+      const Directory aRequestedDir);
 
  private:
   using PopulateDirectoriesPromise = MozPromise<Ok, nsresult, false>;
@@ -238,7 +239,8 @@ class PathUtils::DirectoryCache final {
    * @param aPromise The JS promise to resolve.
    * @param aRequestedDir The requested directory cache entry.
    */
-  void ResolveWithDirectory(Promise* aPromise, const Directory aRequestedDir);
+  void ResolveWithDirectory(dom::Promise* aPromise,
+                            const Directory aRequestedDir);
 
   template <typename T>
   using DirectoryArray =
@@ -255,7 +257,6 @@ class PathUtils::DirectoryCache final {
   };
 };
 
-}  // namespace dom
 }  // namespace mozilla
 
 #endif
diff --git a/xpcom/ioutils/moz.build b/xpcom/ioutils/moz.build
new file mode 100644
index 000000000000..25a638808c59
--- /dev/null
+++ b/xpcom/ioutils/moz.build
@@ -0,0 +1,24 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+with Files("**/*"):
+    BUG_COMPONENT = ("Toolkit", "IOUtils and PathUtils")
+
+EXPORTS.mozilla += [
+    "IOUtils.h",
+    "PathUtils.h",
+]
+
+UNIFIED_SOURCES += [
+    "IOUtils.cpp",
+    "PathUtils.cpp",
+]
+
+MOCHITEST_CHROME_MANIFESTS += ["tests/chrome.toml"]
+
+FINAL_LIBRARY = "xul"
+
+include("/ipc/chromium/chromium-config.mozbuild")
diff --git a/dom/system/tests/ioutils/chrome.toml b/xpcom/ioutils/tests/chrome.toml
similarity index 87%
rename from dom/system/tests/ioutils/chrome.toml
rename to xpcom/ioutils/tests/chrome.toml
index cb0582e006ea..e55cd495d37c 100644
--- a/dom/system/tests/ioutils/chrome.toml
+++ b/xpcom/ioutils/tests/chrome.toml
@@ -37,3 +37,8 @@ run-if = ["os == 'mac'"]
 run-if = ["os == 'win'"]
 
 ["test_ioutils_worker.xhtml"]
+
+["test_pathutils.html"]
+
+["test_pathutils_worker.xhtml"]
+support-files = ["pathutils_worker.js"]
diff --git a/dom/system/tests/ioutils/file_ioutils_test_fixtures.js b/xpcom/ioutils/tests/file_ioutils_test_fixtures.js
similarity index 98%
rename from dom/system/tests/ioutils/file_ioutils_test_fixtures.js
rename to xpcom/ioutils/tests/file_ioutils_test_fixtures.js
index 5d2e5011c954..80236cdd1572 100644
--- a/dom/system/tests/ioutils/file_ioutils_test_fixtures.js
+++ b/xpcom/ioutils/tests/file_ioutils_test_fixtures.js
@@ -1,5 +1,7 @@
 // Utility functions.
 
+/* eslint-env mozilla/simpletest */
+
 Uint8Array.prototype.equals = function equals(other) {
   if (this.byteLength !== other.byteLength) {
     return false;
diff --git a/dom/system/tests/ioutils/file_ioutils_worker.js b/xpcom/ioutils/tests/file_ioutils_worker.js
similarity index 100%
rename from dom/system/tests/ioutils/file_ioutils_worker.js
rename to xpcom/ioutils/tests/file_ioutils_worker.js
diff --git a/dom/system/tests/pathutils_worker.js b/xpcom/ioutils/tests/pathutils_worker.js
similarity index 100%
rename from dom/system/tests/pathutils_worker.js
rename to xpcom/ioutils/tests/pathutils_worker.js
diff --git a/dom/system/tests/ioutils/test_ioutils.html b/xpcom/ioutils/tests/test_ioutils.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils.html
rename to xpcom/ioutils/tests/test_ioutils.html
diff --git a/dom/system/tests/ioutils/test_ioutils_compute_hex_digest.html b/xpcom/ioutils/tests/test_ioutils_compute_hex_digest.html
similarity index 99%
rename from dom/system/tests/ioutils/test_ioutils_compute_hex_digest.html
rename to xpcom/ioutils/tests/test_ioutils_compute_hex_digest.html
index 7a98f83a1fef..977dbd23fba2 100644
--- a/dom/system/tests/ioutils/test_ioutils_compute_hex_digest.html
+++ b/xpcom/ioutils/tests/test_ioutils_compute_hex_digest.html
@@ -1,4 +1,3 @@
-
 <!-- Any copyright is dedicated to the Public Domain.
 - http://creativecommons.org/publicdomain/zero/1.0/ -->
 <!DOCTYPE HTML>
diff --git a/dom/system/tests/ioutils/test_ioutils_copy_move.html b/xpcom/ioutils/tests/test_ioutils_copy_move.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_copy_move.html
rename to xpcom/ioutils/tests/test_ioutils_copy_move.html
diff --git a/dom/system/tests/ioutils/test_ioutils_create_unique.html b/xpcom/ioutils/tests/test_ioutils_create_unique.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_create_unique.html
rename to xpcom/ioutils/tests/test_ioutils_create_unique.html
diff --git a/dom/system/tests/ioutils/test_ioutils_dir_iteration.html b/xpcom/ioutils/tests/test_ioutils_dir_iteration.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_dir_iteration.html
rename to xpcom/ioutils/tests/test_ioutils_dir_iteration.html
diff --git a/dom/system/tests/ioutils/test_ioutils_getfile.html b/xpcom/ioutils/tests/test_ioutils_getfile.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_getfile.html
rename to xpcom/ioutils/tests/test_ioutils_getfile.html
diff --git a/dom/system/tests/ioutils/test_ioutils_mac_xattr.html b/xpcom/ioutils/tests/test_ioutils_mac_xattr.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_mac_xattr.html
rename to xpcom/ioutils/tests/test_ioutils_mac_xattr.html
diff --git a/dom/system/tests/ioutils/test_ioutils_mkdir.html b/xpcom/ioutils/tests/test_ioutils_mkdir.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_mkdir.html
rename to xpcom/ioutils/tests/test_ioutils_mkdir.html
diff --git a/dom/system/tests/ioutils/test_ioutils_read_write.html b/xpcom/ioutils/tests/test_ioutils_read_write.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_read_write.html
rename to xpcom/ioutils/tests/test_ioutils_read_write.html
diff --git a/dom/system/tests/ioutils/test_ioutils_read_write_json.html b/xpcom/ioutils/tests/test_ioutils_read_write_json.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_read_write_json.html
rename to xpcom/ioutils/tests/test_ioutils_read_write_json.html
diff --git a/dom/system/tests/ioutils/test_ioutils_read_write_utf8.html b/xpcom/ioutils/tests/test_ioutils_read_write_utf8.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_read_write_utf8.html
rename to xpcom/ioutils/tests/test_ioutils_read_write_utf8.html
diff --git a/dom/system/tests/ioutils/test_ioutils_remove.html b/xpcom/ioutils/tests/test_ioutils_remove.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_remove.html
rename to xpcom/ioutils/tests/test_ioutils_remove.html
diff --git a/dom/system/tests/ioutils/test_ioutils_set_permissions.html b/xpcom/ioutils/tests/test_ioutils_set_permissions.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_set_permissions.html
rename to xpcom/ioutils/tests/test_ioutils_set_permissions.html
diff --git a/dom/system/tests/ioutils/test_ioutils_stat_set_modification_time.html b/xpcom/ioutils/tests/test_ioutils_stat_set_modification_time.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_stat_set_modification_time.html
rename to xpcom/ioutils/tests/test_ioutils_stat_set_modification_time.html
diff --git a/dom/system/tests/ioutils/test_ioutils_windows_file_attributes.html b/xpcom/ioutils/tests/test_ioutils_windows_file_attributes.html
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_windows_file_attributes.html
rename to xpcom/ioutils/tests/test_ioutils_windows_file_attributes.html
diff --git a/dom/system/tests/ioutils/test_ioutils_worker.xhtml b/xpcom/ioutils/tests/test_ioutils_worker.xhtml
similarity index 100%
rename from dom/system/tests/ioutils/test_ioutils_worker.xhtml
rename to xpcom/ioutils/tests/test_ioutils_worker.xhtml
diff --git a/dom/system/tests/test_pathutils.html b/xpcom/ioutils/tests/test_pathutils.html
similarity index 100%
rename from dom/system/tests/test_pathutils.html
rename to xpcom/ioutils/tests/test_pathutils.html
diff --git a/dom/system/tests/test_pathutils_worker.xhtml b/xpcom/ioutils/tests/test_pathutils_worker.xhtml
similarity index 100%
rename from dom/system/tests/test_pathutils_worker.xhtml
rename to xpcom/ioutils/tests/test_pathutils_worker.xhtml
diff --git a/xpcom/moz.build b/xpcom/moz.build
index 54c04ad8464e..63df48e9f15a 100644
--- a/xpcom/moz.build
+++ b/xpcom/moz.build
@@ -27,6 +27,7 @@ DIRS += [
     "system",
     "../chrome",
     "build",
+    "ioutils",
 ]
 
 if CONFIG["OS_ARCH"] == "WINNT" and CONFIG["MOZ_DEBUG"]: