diff --git a/baselines/asset-esm/package.json b/baselines/asset-esm/package.json
index 654325bc3f..7274906774 100644
--- a/baselines/asset-esm/package.json
+++ b/baselines/asset-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/asset/package.json b/baselines/asset/package.json
index 898cd24056..a5e57fa28e 100644
--- a/baselines/asset/package.json
+++ b/baselines/asset/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/bigquery-storage-esm/package.json b/baselines/bigquery-storage-esm/package.json
index 5fb40fd1bb..a3e8a7e63f 100644
--- a/baselines/bigquery-storage-esm/package.json
+++ b/baselines/bigquery-storage-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/bigquery-storage/package.json b/baselines/bigquery-storage/package.json
index f88519b52d..522118b28c 100644
--- a/baselines/bigquery-storage/package.json
+++ b/baselines/bigquery-storage/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/bigquery-v2-esm/package.json b/baselines/bigquery-v2-esm/package.json
index 526f611170..c25ca866cb 100644
--- a/baselines/bigquery-v2-esm/package.json
+++ b/baselines/bigquery-v2-esm/package.json
@@ -100,7 +100,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/bigquery-v2/package.json b/baselines/bigquery-v2/package.json
index c40888c47c..6239f0b4ae 100644
--- a/baselines/bigquery-v2/package.json
+++ b/baselines/bigquery-v2/package.json
@@ -56,7 +56,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/compute-esm/package.json b/baselines/compute-esm/package.json
index 00b4b26bdd..ece8133b65 100644
--- a/baselines/compute-esm/package.json
+++ b/baselines/compute-esm/package.json
@@ -95,7 +95,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/compute/package.json b/baselines/compute/package.json
index 60bb427929..d468b56a32 100644
--- a/baselines/compute/package.json
+++ b/baselines/compute/package.json
@@ -51,7 +51,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/deprecatedtest-esm/package.json b/baselines/deprecatedtest-esm/package.json
index 8ac93fdd34..9e26f0023f 100644
--- a/baselines/deprecatedtest-esm/package.json
+++ b/baselines/deprecatedtest-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/deprecatedtest/package.json b/baselines/deprecatedtest/package.json
index ce25d383d5..93bf2318b7 100644
--- a/baselines/deprecatedtest/package.json
+++ b/baselines/deprecatedtest/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/disable-packing-test-esm/package.json b/baselines/disable-packing-test-esm/package.json
index 40e5d7ed75..c2a7218f42 100644
--- a/baselines/disable-packing-test-esm/package.json
+++ b/baselines/disable-packing-test-esm/package.json
@@ -99,7 +99,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/disable-packing-test/package.json b/baselines/disable-packing-test/package.json
index 8ec1a89398..2cda483f59 100644
--- a/baselines/disable-packing-test/package.json
+++ b/baselines/disable-packing-test/package.json
@@ -55,7 +55,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/dlp-esm/package.json b/baselines/dlp-esm/package.json
index ba24dafef0..a1a7d5d949 100644
--- a/baselines/dlp-esm/package.json
+++ b/baselines/dlp-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/dlp/package.json b/baselines/dlp/package.json
index af1459c10d..2dff5778b7 100644
--- a/baselines/dlp/package.json
+++ b/baselines/dlp/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/kms-esm/package.json b/baselines/kms-esm/package.json
index 775e1afb9b..e8c0aad652 100644
--- a/baselines/kms-esm/package.json
+++ b/baselines/kms-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/kms/package.json b/baselines/kms/package.json
index edfad67c5d..5c32a28020 100644
--- a/baselines/kms/package.json
+++ b/baselines/kms/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/logging-esm/package.json b/baselines/logging-esm/package.json
index 31c6e28e42..5db75fbdcb 100644
--- a/baselines/logging-esm/package.json
+++ b/baselines/logging-esm/package.json
@@ -96,7 +96,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/logging/package.json b/baselines/logging/package.json
index 672f9cb310..bd453f257c 100644
--- a/baselines/logging/package.json
+++ b/baselines/logging/package.json
@@ -52,7 +52,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/monitoring-esm/package.json b/baselines/monitoring-esm/package.json
index a4e0dbd0b8..75a3c0028c 100644
--- a/baselines/monitoring-esm/package.json
+++ b/baselines/monitoring-esm/package.json
@@ -99,7 +99,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/monitoring/package.json b/baselines/monitoring/package.json
index a2975a414c..d33751cad0 100644
--- a/baselines/monitoring/package.json
+++ b/baselines/monitoring/package.json
@@ -55,7 +55,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/naming-esm/package.json b/baselines/naming-esm/package.json
index c4f79c4489..a349624706 100644
--- a/baselines/naming-esm/package.json
+++ b/baselines/naming-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/naming/package.json b/baselines/naming/package.json
index f5561caea4..24b6905a80 100644
--- a/baselines/naming/package.json
+++ b/baselines/naming/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/redis-esm/package.json b/baselines/redis-esm/package.json
index 3bad898000..d49086be4b 100644
--- a/baselines/redis-esm/package.json
+++ b/baselines/redis-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/redis/package.json b/baselines/redis/package.json
index 738c0d2d7d..a887e53cc5 100644
--- a/baselines/redis/package.json
+++ b/baselines/redis/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/retail-esm/package.json b/baselines/retail-esm/package.json
index 514a206295..c56c033927 100644
--- a/baselines/retail-esm/package.json
+++ b/baselines/retail-esm/package.json
@@ -108,7 +108,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/retail/package.json b/baselines/retail/package.json
index 3bfccdb21a..0f31b6f588 100644
--- a/baselines/retail/package.json
+++ b/baselines/retail/package.json
@@ -64,7 +64,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/routingtest-esm/package.json b/baselines/routingtest-esm/package.json
index df9172cffd..61b8f04f89 100644
--- a/baselines/routingtest-esm/package.json
+++ b/baselines/routingtest-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/routingtest/package.json b/baselines/routingtest/package.json
index f679808e3b..01e7b9b950 100644
--- a/baselines/routingtest/package.json
+++ b/baselines/routingtest/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/showcase-esm/package.json b/baselines/showcase-esm/package.json
index 40e5d7ed75..c2a7218f42 100644
--- a/baselines/showcase-esm/package.json
+++ b/baselines/showcase-esm/package.json
@@ -99,7 +99,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/showcase-legacy-esm/package.json b/baselines/showcase-legacy-esm/package.json
index eac9785115..688075f9ae 100644
--- a/baselines/showcase-legacy-esm/package.json
+++ b/baselines/showcase-legacy-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/showcase-legacy/package.json b/baselines/showcase-legacy/package.json
index d55d8c0d28..e502a0683b 100644
--- a/baselines/showcase-legacy/package.json
+++ b/baselines/showcase-legacy/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/showcase/package.json b/baselines/showcase/package.json
index 8ec1a89398..2cda483f59 100644
--- a/baselines/showcase/package.json
+++ b/baselines/showcase/package.json
@@ -55,7 +55,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/tasks-esm/package.json b/baselines/tasks-esm/package.json
index 77e9694836..cbc837fb62 100644
--- a/baselines/tasks-esm/package.json
+++ b/baselines/tasks-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/tasks/package.json b/baselines/tasks/package.json
index 8b36dc01c0..40aa6a1387 100644
--- a/baselines/tasks/package.json
+++ b/baselines/tasks/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/texttospeech-esm/package.json b/baselines/texttospeech-esm/package.json
index 9edeb1c337..ab086af04e 100644
--- a/baselines/texttospeech-esm/package.json
+++ b/baselines/texttospeech-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/texttospeech/package.json b/baselines/texttospeech/package.json
index 526c628f73..257a8169a6 100644
--- a/baselines/texttospeech/package.json
+++ b/baselines/texttospeech/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/translate-esm/package.json b/baselines/translate-esm/package.json
index ef50c3b140..a1bdda258b 100644
--- a/baselines/translate-esm/package.json
+++ b/baselines/translate-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/translate/package.json b/baselines/translate/package.json
index bb651bc163..eda238d7b7 100644
--- a/baselines/translate/package.json
+++ b/baselines/translate/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/baselines/videointelligence-esm/package.json b/baselines/videointelligence-esm/package.json
index 3cb8d73594..ee086fb61a 100644
--- a/baselines/videointelligence-esm/package.json
+++ b/baselines/videointelligence-esm/package.json
@@ -94,7 +94,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^2.1.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"
diff --git a/baselines/videointelligence/package.json b/baselines/videointelligence/package.json
index 1952d5191e..65e7582e75 100644
--- a/baselines/videointelligence/package.json
+++ b/baselines/videointelligence/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/templates/cjs/typescript_gapic/package.json b/templates/cjs/typescript_gapic/package.json
index cab3bcdeb4..480c195581 100644
--- a/templates/cjs/typescript_gapic/package.json
+++ b/templates/cjs/typescript_gapic/package.json
@@ -50,7 +50,7 @@
     "mocha": "^11.7.1",
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
-    "sinon": "^20.0.0"
+    "sinon": "^21.0.0"
   },
   "engines": {
     "node": ">=v18"
diff --git a/templates/esm/typescript_gapic/package.json b/templates/esm/typescript_gapic/package.json
index c01c36c654..d3ac1f02dc 100644
--- a/templates/esm/typescript_gapic/package.json
+++ b/templates/esm/typescript_gapic/package.json
@@ -96,7 +96,7 @@
     "pack-n-play": "^3.0.0",
     "typescript": "5.8.3",
     "pack-n-play": "^2.1.0",
-    "sinon": "^20.0.0",
+    "sinon": "^21.0.0",
     "ts-loader": "^8.4.0",
     "webpack": "^5.99.9",
     "webpack-cli": "^6.0.1"