diff --git a/composer.json b/composer.json
index a8c25bdb8..a28cb2ddf 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
         "silverstripe/vendor-plugin": "^2"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.6",
+        "phpunit/phpunit": "^11.3",
         "silverstripe/frameworktest": "^2",
         "squizlabs/php_codesniffer": "^3.7",
         "silverstripe/standards": "^1",
diff --git a/tests/php/LeftAndMainTest.php b/tests/php/LeftAndMainTest.php
index 9bb4c6697..d9cc7bb9e 100644
--- a/tests/php/LeftAndMainTest.php
+++ b/tests/php/LeftAndMainTest.php
@@ -19,6 +19,7 @@
 use stdClass;
 use ReflectionObject;
 use InvalidArgumentException;
+use PHPUnit\Framework\Attributes\DataProvider;
 
 class LeftAndMainTest extends FunctionalTest
 {
@@ -218,21 +219,19 @@ public function testDisableHelpLinks()
         $this->assertCount(0, $helpLinks);
     }
 
-    /**
-     * @dataProvider provideTestCMSVersionNumber
-     */
+    #[DataProvider('provideTestCMSVersionNumber')]
     public function testCMSVersionNumber($frameworkVersion, $expected)
     {
         $versionProvider = $this
             ->getMockBuilder(VersionProvider::class)
-            ->setMethods(['getModules', 'getModuleVersionFromComposer'])
+            ->onlyMethods(['getModules', 'getModuleVersionFromComposer'])
             ->getMock();
         $data = ['silverstripe/framework' => $frameworkVersion];
         $versionProvider->method('getModules')->willReturn($data);
         $versionProvider->method('getModuleVersionFromComposer')->willReturn($data);
         $leftAndMain = $this
             ->getMockBuilder(LeftAndMain::class)
-            ->setMethods(['getVersionProvider'])
+            ->onlyMethods(['getVersionProvider'])
             ->getMock();
         $leftAndMain->method('getVersionProvider')->willReturn($versionProvider);
         $this->assertSame($expected, $leftAndMain->CMSVersionNumber());
@@ -241,7 +240,7 @@ public function testCMSVersionNumber($frameworkVersion, $expected)
     /**
      * @return array
      */
-    public function provideTestCMSVersionNumber()
+    public static function provideTestCMSVersionNumber()
     {
         return [
             ['4.9.1', '4.9'],
@@ -290,7 +289,7 @@ public function testValidationResult()
         $this->assertSame($result->messages[0]->message, MyTree::INVALID_CONTENT_MESSAGE);
     }
 
-    public function provideJsonSuccess(): array
+    public static function provideJsonSuccess(): array
     {
         return [
             [
@@ -338,9 +337,7 @@ public function provideJsonSuccess(): array
         ];
     }
 
-    /**
-     * @dataProvider provideJsonSuccess
-     */
+    #[DataProvider('provideJsonSuccess')]
     public function testJsonSuccess(
         int $statusCode,
         ?array $data,
@@ -360,7 +357,7 @@ public function testJsonSuccess(
         $this->assertSame($expectedBody, $response->getBody());
     }
 
-    public function provideJsonError(): array
+    public static function provideJsonError(): array
     {
         return [
             [
@@ -406,9 +403,7 @@ public function provideJsonError(): array
         ];
     }
 
-    /**
-     * @dataProvider provideJsonError
-     */
+    #[DataProvider('provideJsonError')]
     public function testJsonError(
         int $statusCode,
         ?string $errorMessage,
diff --git a/tests/php/ModelAdminTest.php b/tests/php/ModelAdminTest.php
index d4fea6ade..817d5bc9f 100644
--- a/tests/php/ModelAdminTest.php
+++ b/tests/php/ModelAdminTest.php
@@ -220,14 +220,14 @@ public function testGetManagedModels()
     public function testGetManagedModelTabs()
     {
         $mock = $this->getMockBuilder(ModelAdminTest\MultiModelAdmin::class)
-            ->setMethods(['getManagedModels'])
+            ->onlyMethods(['getManagedModels'])
             ->getMock();
 
         // `getManagedModelTabs` relies on `getManagedModels` whose output format has changed within the 4.x line.
         // We need to mock `getManagedModels` so it returns both the legacy and updated format.
         $mock->expects($this->atLeastOnce())
             ->method('getManagedModels')
-            ->will($this->returnValue([
+            ->willReturn([
                 'Player' => [
                     'dataClass' => Player::class,
                     'title' => 'Ice Hockey Players'
@@ -239,7 +239,7 @@ public function testGetManagedModelTabs()
                     'dataClass' => Player::class,
                     'title' => 'Cricket Players',
                 ],
-            ]));
+            ]);
 
 
         $tabs = $mock->getManagedModelTabs()->toNestedArray();
@@ -386,11 +386,11 @@ public function testGetModelTabForModelClassNoSpec()
         // We need to mock `getManagedModels` to test the legacy format.
         $mock->expects($this->atLeastOnce())
             ->method('getManagedModels')
-            ->will($this->returnValue([
+            ->willReturn([
                 Player::class => [
                     'title' => 'Rugby Players'
                 ],
-            ]));
+            ]);
 
         $reflectionMethod = new ReflectionMethod($mock, 'getModelTabForModelClass');
         $reflectionMethod->setAccessible(true);