diff --git a/.ci.yaml b/.ci.yaml
index 71c68a073c52..ac64230f5e26 100644
--- a/.ci.yaml
+++ b/.ci.yaml
@@ -98,12 +98,12 @@ platform_properties:
         [
           {"dependency": "ruby", "version": "ruby_3.1-pod_1.13"}
         ]
-      os: Mac-15.7|Mac-26.6
+      os: Mac-26.6
       device_type: none
       cpu: arm64
       $flutter/osx_sdk : >-
         {
-          "sdk_version": "17c52"
+          "sdk_version": "27a266a"
         }
 
 targets:
diff --git a/.ci/scripts/create_simulator.sh b/.ci/scripts/create_simulator.sh
index e43100266004..85dad3a8a48b 100755
--- a/.ci/scripts/create_simulator.sh
+++ b/.ci/scripts/create_simulator.sh
@@ -9,7 +9,7 @@ set -o pipefail
 # The name here must match remove_simulator.sh
 readonly DEVICE_NAME=Flutter-iPhone
 readonly DEVICE=com.apple.CoreSimulator.SimDeviceType.iPhone-14
-readonly OS=com.apple.CoreSimulator.SimRuntime.iOS-26-2
+readonly OS=com.apple.CoreSimulator.SimRuntime.iOS-27-0
 
 # Delete any existing devices named Flutter-iPhone. Having more than one may
 # cause issues when builds target the device.
diff --git a/.ci/targets/ios_platform_tests.yaml b/.ci/targets/ios_platform_tests.yaml
index f0d0b6b95663..c4fe6d89feea 100644
--- a/.ci/targets/ios_platform_tests.yaml
+++ b/.ci/targets/ios_platform_tests.yaml
@@ -22,7 +22,7 @@ tasks:
   - name: native test
     script: .ci/scripts/tool_runner.sh
     # Simulator name and version must match name and version in create_simulator.sh
-    args: ["native-test", "--ios", "--ios-destination", "platform=iOS Simulator,name=Flutter-iPhone,OS=26.2", "--xcode-warnings-exceptions=script/configs/xcode_warnings_exceptions.yaml"]
+    args: ["native-test", "--ios", "--ios-destination", "platform=iOS Simulator,name=Flutter-iPhone,OS=27.0", "--xcode-warnings-exceptions=script/configs/xcode_warnings_exceptions.yaml"]
   - name: boot simulator
     # Ensure simulator is still booted
     script: .ci/scripts/boot_simulator.sh
diff --git a/packages/pigeon/tool/shared/test_suites.dart b/packages/pigeon/tool/shared/test_suites.dart
index 17e064adff9c..dbfe440adf79 100644
--- a/packages/pigeon/tool/shared/test_suites.dart
+++ b/packages/pigeon/tool/shared/test_suites.dart
@@ -444,8 +444,8 @@ Future<int> _runIOSPluginUnitTests(String testPluginPath) async {
 
   const deviceName = 'Pigeon-Test-iPhone';
   const deviceType = 'com.apple.CoreSimulator.SimDeviceType.iPhone-14';
-  const deviceRuntime = 'com.apple.CoreSimulator.SimRuntime.iOS-26-2';
-  const deviceOS = '26.2';
+  const deviceRuntime = 'com.apple.CoreSimulator.SimRuntime.iOS-27-0';
+  const deviceOS = '27.0';
   await _createSimulator(deviceName, deviceType, deviceRuntime);
   return runXcodeBuild(
     '$examplePath/ios',