diff --git a/build/moz.configure/toolchain.configure b/build/moz.configure/toolchain.configure
index 769ac0379045..282c2d3dee48 100644
--- a/build/moz.configure/toolchain.configure
+++ b/build/moz.configure/toolchain.configure
@@ -233,7 +233,7 @@ with only_when(host_is_osx | target_is_osx):
     )
 
     def mac_sdk_min_version():
-        return "15.4"
+        return "15.5"
 
     @depends(
         "--with-macos-sdk",
diff --git a/python/mozbuild/mozbuild/test/configure/macos_fake_sdk/SDKSettings.plist b/python/mozbuild/mozbuild/test/configure/macos_fake_sdk/SDKSettings.plist
index 51da3cc35bc3..1cde2b8a25e2 100644
--- a/python/mozbuild/mozbuild/test/configure/macos_fake_sdk/SDKSettings.plist
+++ b/python/mozbuild/mozbuild/test/configure/macos_fake_sdk/SDKSettings.plist
@@ -3,6 +3,6 @@
 <plist version="1.0">
 <dict>
         <key>Version</key>
-        <string>15.4</string>
+        <string>15.5</string>
 </dict>
 </plist>
diff --git a/taskcluster/kinds/toolchain/macos-sdk.yml b/taskcluster/kinds/toolchain/macos-sdk.yml
index 46a577fab149..e342d435298c 100644
--- a/taskcluster/kinds/toolchain/macos-sdk.yml
+++ b/taskcluster/kinds/toolchain/macos-sdk.yml
@@ -43,10 +43,23 @@ macosx64-sdk-15.4:
             - Library/Developer/CommandLineTools/SDKs/MacOSX15.4.sdk
         toolchain-artifact: project/gecko/mac-sdk/MacOSX15.4.sdk.tar.zst
         toolchain-alias:
-            - macosx64-sdk
             - macosx64-sdk-toolchain
             - MacOSX15.4.sdk
 
+macosx64-sdk-15.5:
+    description: "MacOSX15.5 SDK"
+    treeherder:
+        symbol: TM(sdk15.5)
+    run:
+        arguments:
+            - https://swcdn.apple.com/content/downloads/52/01/082-41241-A_0747ZN8FHV/dectd075r63pppkkzsb75qk61s0lfee22j/CLTools_macOSNMOS_SDK.pkg
+            - fb7c555e823b830279394e52c7d439bd287a9d8b007883fa0595962a240d488b5613f8cc8d1cc9657909de9367417652564f3df66e238a47bbc87244f5205056
+            - Library/Developer/CommandLineTools/SDKs/MacOSX15.5.sdk
+        toolchain-artifact: project/gecko/mac-sdk/MacOSX15.5.sdk.tar.zst
+        toolchain-alias:
+            - macosx64-sdk
+            - MacOSX15.5.sdk
+
 ios-sdk-18.4:
     description: "iPhoneOS18.4 SDK"
     treeherder: