diff --git a/ChangeLog-12.0.md b/ChangeLog-12.0.md
index afe23a0ada4..0023d08bd10 100644
--- a/ChangeLog-12.0.md
+++ b/ChangeLog-12.0.md
@@ -6,6 +6,7 @@ All notable changes of the PHPUnit 12.0 release series are documented in this fi
 
 ### Removed
 
+* [#5215](https://github.com/sebastianbergmann/phpunit/issues/5215): `TestCase::iniSet()`
 * [#5246](https://github.com/sebastianbergmann/phpunit/issues/5246): `TestCase::createTestProxy()`
 * [#5247](https://github.com/sebastianbergmann/phpunit/issues/5247): `TestCase::getMockForAbstractClass()`
 * [#5248](https://github.com/sebastianbergmann/phpunit/issues/5248): `TestCase::getMockFromWsdl()`
diff --git a/DEPRECATIONS.md b/DEPRECATIONS.md
index 8e3306c66da..6d93b95eac0 100644
--- a/DEPRECATIONS.md
+++ b/DEPRECATIONS.md
@@ -47,7 +47,6 @@ This functionality is currently [hard-deprecated](https://phpunit.de/backward-co
 | Issue                                                             | Description                                                 | Since  | Replacement                                                                             |
 |-------------------------------------------------------------------|-------------------------------------------------------------|--------|-----------------------------------------------------------------------------------------|
 | [#4505](https://github.com/sebastianbergmann/phpunit/issues/4505) | Metadata in doc-comments                                    | 10.3.0 | Metadata in attributes                                                                  |
-| [#5214](https://github.com/sebastianbergmann/phpunit/issues/5214) | `TestCase::iniSet()`                                        | 10.3.0 |                                                                                         |
 | [#5216](https://github.com/sebastianbergmann/phpunit/issues/5216) | `TestCase::setLocale()`                                     | 10.3.0 |                                                                                         |
 | [#5800](https://github.com/sebastianbergmann/phpunit/issues/5800) | Targeting traits with `#[CoversClass]` and `#[UsesClass]`   | 11.2.0 | `#[CoversClass]` and `#[UsesClass]` also target the traits used by the targeted classes |
 | [#5951](https://github.com/sebastianbergmann/phpunit/issues/5951) | `includeUncoveredFiles` configuration option                | 11.4.0 |                                                                                         |
diff --git a/src/Framework/TestCase.php b/src/Framework/TestCase.php
index 2d9d8f6b5b3..65e58f5e17d 100644
--- a/src/Framework/TestCase.php
+++ b/src/Framework/TestCase.php
@@ -31,7 +31,6 @@
 use function getcwd;
 use function implode;
 use function in_array;
-use function ini_set;
 use function is_array;
 use function is_callable;
 use function is_int;
@@ -176,11 +175,6 @@ abstract class TestCase extends Assert implements Reorderable, SelfDescribing, T
      */
     private array $dependencyInput = [];
 
-    /**
-     * @var array<string,string>
-     */
-    private array $iniSettings = [];
-
     /**
      * @var array<int, non-empty-string>
      */
@@ -645,7 +639,6 @@ final public function runBare(): void
         $this->restoreGlobalErrorExceptionHandlers();
         $this->restoreGlobalState();
         $this->unregisterCustomComparators();
-        $this->cleanupIniSettings();
         $this->cleanupLocaleSettings();
         libxml_clear_errors();
 
@@ -1241,39 +1234,6 @@ final protected function runTest(): mixed
         return $testResult;
     }
 
-    /**
-     * This method is a wrapper for the ini_set() function that automatically
-     * resets the modified php.ini setting to its original value after the
-     * test is run.
-     *
-     * @throws Exception
-     *
-     * @deprecated https://github.com/sebastianbergmann/phpunit/issues/5214
-     *
-     * @codeCoverageIgnore
-     */
-    final protected function iniSet(string $varName, string $newValue): void
-    {
-        Event\Facade::emitter()->testTriggeredPhpunitDeprecation(
-            $this->valueObjectForEvents(),
-            'iniSet() is deprecated and will be removed in PHPUnit 12 without replacement.',
-        );
-
-        $currentValue = ini_set($varName, $newValue);
-
-        if ($currentValue !== false) {
-            $this->iniSettings[$varName] = $currentValue;
-        } else {
-            throw new Exception(
-                sprintf(
-                    'INI setting "%s" could not be set to "%s".',
-                    $varName,
-                    $newValue,
-                ),
-            );
-        }
-    }
-
     /**
      * This method is a wrapper for the setlocale() function that automatically
      * resets the locale to its original value after the test is run.
@@ -1959,15 +1919,6 @@ private function unregisterCustomComparators(): void
         $this->customComparators = [];
     }
 
-    private function cleanupIniSettings(): void
-    {
-        foreach ($this->iniSettings as $varName => $oldValue) {
-            ini_set($varName, $oldValue);
-        }
-
-        $this->iniSettings = [];
-    }
-
     private function cleanupLocaleSettings(): void
     {
         foreach ($this->locale as $category => $locale) {