diff --git a/packages/rulesets/CHANGELOG.md b/packages/rulesets/CHANGELOG.md
index f4bb1a521..df8f5d01c 100644
--- a/packages/rulesets/CHANGELOG.md
+++ b/packages/rulesets/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 ### Patches
 
+- [MutabilityWithReadOnly] Add null check to given clause filter
 - Reduce package size by 88% (6.3MB → 745KB unpacked) by excluding test files and source TypeScript files
 - Upgrade minimum required Node.js version from 18 to 20
 
diff --git a/packages/rulesets/generated/spectral/az-arm.js b/packages/rulesets/generated/spectral/az-arm.js
index bb2146d44..5b1c4682b 100644
--- a/packages/rulesets/generated/spectral/az-arm.js
+++ b/packages/rulesets/generated/spectral/az-arm.js
@@ -1065,7 +1065,7 @@ const ruleset$1 = {
             severity: "error",
             resolved: true,
             formats: [oas2],
-            given: ["$[paths,'x-ms-paths']..*[?(@.readOnly !== undefined && @['x-ms-mutability'] !== undefined)]"],
+            given: ["$[paths,'x-ms-paths']..*[?(@ != null && @.readOnly !== undefined && @['x-ms-mutability'] !== undefined)]"],
             then: {
                 function: mutabilityWithReadOnly,
             },
diff --git a/packages/rulesets/generated/spectral/az-common.js b/packages/rulesets/generated/spectral/az-common.js
index 8626815ea..828f94750 100644
--- a/packages/rulesets/generated/spectral/az-common.js
+++ b/packages/rulesets/generated/spectral/az-common.js
@@ -819,7 +819,7 @@ const ruleset = {
             severity: "error",
             resolved: true,
             formats: [oas2],
-            given: ["$[paths,'x-ms-paths']..*[?(@.readOnly !== undefined && @['x-ms-mutability'] !== undefined)]"],
+            given: ["$[paths,'x-ms-paths']..*[?(@ != null && @.readOnly !== undefined && @['x-ms-mutability'] !== undefined)]"],
             then: {
                 function: mutabilityWithReadOnly,
             },
diff --git a/packages/rulesets/generated/spectral/az-dataplane.js b/packages/rulesets/generated/spectral/az-dataplane.js
index 9052b283a..63fd59ad0 100644
--- a/packages/rulesets/generated/spectral/az-dataplane.js
+++ b/packages/rulesets/generated/spectral/az-dataplane.js
@@ -849,7 +849,7 @@ const ruleset$1 = {
             severity: "error",
             resolved: true,
             formats: [oas2],
-            given: ["$[paths,'x-ms-paths']..*[?(@.readOnly !== undefined && @['x-ms-mutability'] !== undefined)]"],
+            given: ["$[paths,'x-ms-paths']..*[?(@ != null && @.readOnly !== undefined && @['x-ms-mutability'] !== undefined)]"],
             then: {
                 function: mutabilityWithReadOnly,
             },
diff --git a/packages/rulesets/src/spectral/az-common.ts b/packages/rulesets/src/spectral/az-common.ts
index 605e344cc..26a97f2dc 100644
--- a/packages/rulesets/src/spectral/az-common.ts
+++ b/packages/rulesets/src/spectral/az-common.ts
@@ -263,7 +263,7 @@ const ruleset: any = {
       severity: "error",
       resolved: true,
       formats: [oas2],
-      given: ["$[paths,'x-ms-paths']..*[?(@.readOnly !== undefined && @['x-ms-mutability'] !== undefined)]"],
+      given: ["$[paths,'x-ms-paths']..*[?(@ != null && @.readOnly !== undefined && @['x-ms-mutability'] !== undefined)]"],
       then: {
         function: mutabilityWithReadOnly,
       },
diff --git a/packages/rulesets/src/spectral/test/mutability-with-read-only.test.ts b/packages/rulesets/src/spectral/test/mutability-with-read-only.test.ts
index 9ccaced3f..69d8c5349 100644
--- a/packages/rulesets/src/spectral/test/mutability-with-read-only.test.ts
+++ b/packages/rulesets/src/spectral/test/mutability-with-read-only.test.ts
@@ -134,3 +134,19 @@ test("MutabilityWithReadOnly: properties ignored by given clause", () => {
     expect(results.length).toBe(0);
   });
 });
+
+test("MutabilityWithReadOnly: null property values are filtered by given clause", () => {
+  const myOpenApiDocument = createOpenApiDoc({
+    nullProperty: null,
+    validProperty: {
+      type: "string",
+      readOnly: true,
+      "x-ms-mutability": ["read"],
+    },
+  });
+  return linter.run(myOpenApiDocument).then((results) => {
+    // Null property should be filtered out by the given clause (@ != null check)
+    // Only the valid property should pass through, and it's valid so 0 errors
+    expect(results.length).toBe(0);
+  });
+});