diff --git a/src/wp-admin/includes/ajax-actions.php b/src/wp-admin/includes/ajax-actions.php
index 2af08fba70af9..935902553fc12 100644
--- a/src/wp-admin/includes/ajax-actions.php
+++ b/src/wp-admin/includes/ajax-actions.php
@@ -2489,19 +2489,8 @@ function wp_ajax_delete_inactive_widgets() {
 	/** This action is documented in wp-admin/widgets-form.php */
 	do_action( 'sidebar_admin_setup' );
 
-	$sidebars_widgets = wp_get_sidebars_widgets();
-
-	foreach ( $sidebars_widgets['wp_inactive_widgets'] as $key => $widget_id ) {
-		$pieces       = explode( '-', $widget_id );
-		$multi_number = array_pop( $pieces );
-		$id_base      = implode( '-', $pieces );
-		$widget       = get_option( 'widget_' . $id_base );
-		unset( $widget[ $multi_number ] );
-		update_option( 'widget_' . $id_base, $widget );
-		unset( $sidebars_widgets['wp_inactive_widgets'][ $key ] );
-	}
-
-	wp_set_sidebars_widgets( $sidebars_widgets );
+	require_once ABSPATH . 'wp-admin/includes/widgets.php';
+	wp_delete_inactive_widgets();
 
 	wp_die();
 }
diff --git a/src/wp-admin/includes/widgets.php b/src/wp-admin/includes/widgets.php
index e751602866b0d..5d93d2a4b9eb8 100644
--- a/src/wp-admin/includes/widgets.php
+++ b/src/wp-admin/includes/widgets.php
@@ -326,3 +326,32 @@ function wp_widget_control( $sidebar_args ) {
 function wp_widgets_access_body_class( $classes ) {
 	return "$classes widgets_access ";
 }
+
+/**
+ * Removes all widgets from the inactive widgets sidebar and their corresponding settings.
+ *
+ * @since 7.1.0
+ */
+function wp_delete_inactive_widgets(): void {
+	$sidebars_widgets = wp_get_sidebars_widgets();
+
+	$inactive_widgets = $sidebars_widgets['wp_inactive_widgets'] ?? array();
+	if ( ! is_array( $inactive_widgets ) || 0 === count( $inactive_widgets ) ) {
+		return;
+	}
+
+	foreach ( $inactive_widgets as $widget_id ) {
+		$pieces       = explode( '-', $widget_id );
+		$multi_number = array_pop( $pieces );
+		$id_base      = implode( '-', $pieces );
+		$widget       = get_option( 'widget_' . $id_base );
+
+		if ( is_array( $widget ) ) {
+			unset( $widget[ $multi_number ] );
+			update_option( 'widget_' . $id_base, $widget );
+		}
+	}
+
+	$sidebars_widgets['wp_inactive_widgets'] = array();
+	wp_set_sidebars_widgets( $sidebars_widgets );
+}
diff --git a/tests/phpunit/tests/widgets.php b/tests/phpunit/tests/widgets.php
index 8eb5914c9400d..6d2bda524d149 100644
--- a/tests/phpunit/tests/widgets.php
+++ b/tests/phpunit/tests/widgets.php
@@ -866,6 +866,136 @@ public function test_wp_widget_control() {
 		}
 	}
 
+	/**
+	 * @covers ::wp_delete_inactive_widgets
+	 * @ticket 65414
+	 */
+	public function test_wp_delete_inactive_widgets_removes_settings_and_empties_sidebar() {
+		require_once ABSPATH . 'wp-admin/includes/widgets.php';
+
+		update_option(
+			'widget_search',
+			array(
+				2              => array( 'title' => 'Search 2' ),
+				3              => array( 'title' => 'Search 3' ),
+				'_multiwidget' => 1,
+			)
+		);
+		update_option(
+			'widget_text',
+			array(
+				5              => array( 'text' => 'Text 5' ),
+				'_multiwidget' => 1,
+			)
+		);
+
+		wp_set_sidebars_widgets(
+			array(
+				'sidebar-1'           => array( 'search-3' ),
+				'wp_inactive_widgets' => array( 'search-2', 'text-5' ),
+			)
+		);
+
+		wp_delete_inactive_widgets();
+
+		$sidebars_widgets = wp_get_sidebars_widgets();
+		$this->assertSame( array(), $sidebars_widgets['wp_inactive_widgets'] );
+		$this->assertSame( array( 'search-3' ), $sidebars_widgets['sidebar-1'] );
+
+		$search_settings = get_option( 'widget_search' );
+		$this->assertArrayNotHasKey( 2, $search_settings );
+		$this->assertArrayHasKey( 3, $search_settings );
+
+		$text_settings = get_option( 'widget_text' );
+		$this->assertArrayNotHasKey( 5, $text_settings );
+	}
+
+	/**
+	 * @covers ::wp_delete_inactive_widgets
+	 * @ticket 65414
+	 */
+	public function test_wp_delete_inactive_widgets_with_no_inactive_widgets_key() {
+		require_once ABSPATH . 'wp-admin/includes/widgets.php';
+
+		wp_set_sidebars_widgets(
+			array(
+				'sidebar-1' => array( 'search-2' ),
+			)
+		);
+
+		wp_delete_inactive_widgets();
+
+		$sidebars_widgets = wp_get_sidebars_widgets();
+		$this->assertArrayNotHasKey( 'wp_inactive_widgets', $sidebars_widgets );
+		$this->assertSame( array( 'search-2' ), $sidebars_widgets['sidebar-1'] );
+	}
+
+	/**
+	 * @covers ::wp_delete_inactive_widgets
+	 * @ticket 65414
+	 */
+	public function test_wp_delete_inactive_widgets_with_empty_inactive_widgets() {
+		require_once ABSPATH . 'wp-admin/includes/widgets.php';
+
+		wp_set_sidebars_widgets(
+			array(
+				'sidebar-1'           => array( 'search-2' ),
+				'wp_inactive_widgets' => array(),
+			)
+		);
+
+		wp_delete_inactive_widgets();
+
+		$sidebars_widgets = wp_get_sidebars_widgets();
+		$this->assertSame( array(), $sidebars_widgets['wp_inactive_widgets'] );
+		$this->assertSame( array( 'search-2' ), $sidebars_widgets['sidebar-1'] );
+	}
+
+	/**
+	 * A corrupted `wp_inactive_widgets` entry (not an array) must not raise a
+	 * TypeError from count() on PHP 8.
+	 *
+	 * @covers ::wp_delete_inactive_widgets
+	 * @ticket 65414
+	 */
+	public function test_wp_delete_inactive_widgets_with_non_array_inactive_widgets_does_not_throw() {
+		require_once ABSPATH . 'wp-admin/includes/widgets.php';
+
+		wp_set_sidebars_widgets(
+			array(
+				'sidebar-1'           => array( 'search-2' ),
+				'wp_inactive_widgets' => 'not-an-array',
+			)
+		);
+
+		wp_delete_inactive_widgets();
+
+		$sidebars_widgets = wp_get_sidebars_widgets();
+		$this->assertSame( 'not-an-array', $sidebars_widgets['wp_inactive_widgets'] );
+		$this->assertSame( array( 'search-2' ), $sidebars_widgets['sidebar-1'] );
+	}
+
+	/**
+	 * @covers ::wp_delete_inactive_widgets
+	 * @ticket 65414
+	 */
+	public function test_wp_delete_inactive_widgets_skips_non_array_widget_option() {
+		require_once ABSPATH . 'wp-admin/includes/widgets.php';
+
+		update_option( 'widget_search', 'corrupted-data' );
+
+		wp_set_sidebars_widgets(
+			array(
+				'wp_inactive_widgets' => array( 'search-2' ),
+			)
+		);
+
+		wp_delete_inactive_widgets();
+
+		$this->assertSame( 'corrupted-data', get_option( 'widget_search' ) );
+		$this->assertSame( array(), wp_get_sidebars_widgets()['wp_inactive_widgets'] );
+	}
+
 	public function test_the_widget_custom_before_title_arg() {
 		register_widget( 'WP_Widget_Text' );