diff --git a/common/changes/@microsoft/rush-lib_2026-09-16-185000.json b/common/changes/@microsoft/rush-lib_2026-09-16-185000.json
new file mode 100644
index 0000000000..30a1aa8c58
--- /dev/null
+++ b/common/changes/@microsoft/rush-lib_2026-09-16-185000.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Upgrade the `pnpm-sync-lib` dependency to 0.3.5 to add support for pnpm 11.",
+      "type": "patch",
+      "packageName": "@microsoft/rush-lib"
+    }
+  ],
+  "packageName": "@microsoft/rush-lib",
+  "email": "rushbot@users.noreply.github.com"
+}
diff --git a/common/config/subspaces/build-tests-subspace/pnpm-lock.yaml b/common/config/subspaces/build-tests-subspace/pnpm-lock.yaml
index 098384d086..aee553b57d 100644
--- a/common/config/subspaces/build-tests-subspace/pnpm-lock.yaml
+++ b/common/config/subspaces/build-tests-subspace/pnpm-lock.yaml
@@ -3087,8 +3087,8 @@ packages:
     resolution: {integrity: sha512-TfySrs/5nm8fQJDcBDuUng3VOUKsd7S+zqvbOTiGXHfxX4wK31ard+hoNuvkicM/2YFzlpDgABOevKSsB4G/FA==}
     engines: {node: '>= 6'}
 
-  pnpm-sync-lib@0.3.4:
-    resolution: {integrity: sha512-ZgRR+j6B+VUrolPBswPvXBnCyxg39Zfw3ShNCTuCrOFG1V29V4EyXaA1rDDMjdhpF85QYp2NEUjeHAm02A2E/A==}
+  pnpm-sync-lib@0.3.5:
+    resolution: {integrity: sha512-6QXYyNpZYJQwnobDXc5bQlTJ7QoRf+n9qVO4ufbbZGOQlNocFZKl1/WkD6qeweFQthTSUuVBA8Le+31XOHlVmA==}
 
   possible-typed-array-names@1.1.0:
     resolution: {integrity: sha512-/+5VFTchJDoVj3bhoqi6UeymcD00DAwb1nJwamzPvHEszJ4FpF6SNNbUbOS8yI56qHzdV8eK0qEfOSiodkTdxg==}
@@ -4384,7 +4384,7 @@ snapshots:
       js-yaml: 4.1.1
       npm-package-arg: 6.1.1
       object-hash: 3.0.0
-      pnpm-sync-lib: 0.3.4
+      pnpm-sync-lib: 0.3.5
       read-package-tree: 5.1.6
       rxjs: 6.6.7
       semver: 7.7.4
@@ -7612,7 +7612,7 @@ snapshots:
 
   pirates@4.0.7: {}
 
-  pnpm-sync-lib@0.3.4:
+  pnpm-sync-lib@0.3.5:
     dependencies:
       '@pnpm/dependency-path-pnpm-v10': '@pnpm/dependency-path@1000.0.9'
       '@pnpm/dependency-path-pnpm-v8': '@pnpm/dependency-path@2.1.8'
diff --git a/common/config/subspaces/default/pnpm-lock.yaml b/common/config/subspaces/default/pnpm-lock.yaml
index 3c8af9d4de..676d74cd7c 100644
--- a/common/config/subspaces/default/pnpm-lock.yaml
+++ b/common/config/subspaces/default/pnpm-lock.yaml
@@ -4260,8 +4260,8 @@ importers:
         specifier: 3.0.0
         version: 3.0.0
       pnpm-sync-lib:
-        specifier: 0.3.4
-        version: 0.3.4
+        specifier: 0.3.5
+        version: 0.3.5
       read-package-tree:
         specifier: ~5.1.5
         version: 5.1.6
@@ -16451,8 +16451,8 @@ packages:
     resolution: {integrity: sha512-7Wjy+9E3WwLOEL30D+m8TSTF7qJJUJLONBnwQp0518siuMxUQUbgZwssaFX+QKlZkjHZcw/IpZCt/H0srrntSg==}
     engines: {node: '>=6'}
 
-  pnpm-sync-lib@0.3.4:
-    resolution: {integrity: sha512-ZgRR+j6B+VUrolPBswPvXBnCyxg39Zfw3ShNCTuCrOFG1V29V4EyXaA1rDDMjdhpF85QYp2NEUjeHAm02A2E/A==}
+  pnpm-sync-lib@0.3.5:
+    resolution: {integrity: sha512-6QXYyNpZYJQwnobDXc5bQlTJ7QoRf+n9qVO4ufbbZGOQlNocFZKl1/WkD6qeweFQthTSUuVBA8Le+31XOHlVmA==}
 
   polished@4.3.1:
     resolution: {integrity: sha512-OBatVyC/N7SCW/FaDHrSd+vn0o5cS855TOmYi4OkdWUMSJCET/xip//ch8xGUvtr3i44X9LVyWwQlRMTN3pwSA==}
@@ -35224,7 +35224,7 @@ snapshots:
     transitivePeerDependencies:
       - typescript
 
-  pnpm-sync-lib@0.3.4:
+  pnpm-sync-lib@0.3.5:
     dependencies:
       '@pnpm/dependency-path-pnpm-v10': '@pnpm/dependency-path@1000.0.9'
       '@pnpm/dependency-path-pnpm-v8': '@pnpm/dependency-path@2.1.8'
diff --git a/common/config/validation/rush-package-lock.json b/common/config/validation/rush-package-lock.json
index b2fce6d630..3488db5ed1 100644
--- a/common/config/validation/rush-package-lock.json
+++ b/common/config/validation/rush-package-lock.json
@@ -547,7 +547,7 @@
         "js-yaml": "~4.1.0",
         "npm-package-arg": "~6.1.0",
         "object-hash": "3.0.0",
-        "pnpm-sync-lib": "0.3.4",
+        "pnpm-sync-lib": "0.3.5",
         "read-package-tree": "~5.1.5",
         "rxjs": "~6.6.7",
         "semver": "~7.7.4",
@@ -3684,8 +3684,8 @@
       }
     },
     "node_modules/pnpm-sync-lib": {
-      "version": "0.3.4",
-      "integrity": "sha1-WqvCl3akqkRBeaO4auAdpdCtTU8=",
+      "version": "0.3.5",
+      "integrity": "sha1-dPlwrJvHri8NQiRh6zqC23A8a7Y=",
       "license": "MIT",
       "dependencies": {
         "@pnpm/dependency-path-pnpm-v10": "npm:@pnpm/dependency-path@^1000.0.9",
diff --git a/libraries/rush-lib/package.json b/libraries/rush-lib/package.json
index 9eebb7059c..72c0cb4b5f 100644
--- a/libraries/rush-lib/package.json
+++ b/libraries/rush-lib/package.json
@@ -73,7 +73,7 @@
     "js-yaml": "~4.1.0",
     "npm-package-arg": "~6.1.0",
     "object-hash": "3.0.0",
-    "pnpm-sync-lib": "0.3.4",
+    "pnpm-sync-lib": "0.3.5",
     "read-package-tree": "~5.1.5",
     "rxjs": "~6.6.7",
     "semver": "~7.7.4",