diff --git a/src/wp-admin/includes/dashboard-on-this-day.php b/src/wp-admin/includes/dashboard-on-this-day.php
index 1939f8ca4b0e3..23a411e7e34e8 100644
--- a/src/wp-admin/includes/dashboard-on-this-day.php
+++ b/src/wp-admin/includes/dashboard-on-this-day.php
@@ -7,48 +7,6 @@
  * @since 7.1.0
  */
 
-/**
- * Registers the On This Day dashboard widget.
- *
- * Designed to be the single entry point called from the dashboard setup
- * routine. The widget is always registered so that it remains available in
- * Screen Options and keeps its user-customized position. When there are no
- * matching posts, a marker class is added to the postbox so the widget can be
- * hidden with CSS.
- *
- * @since 7.1.0
- */
-function wp_dashboard_on_this_day_setup() {
-	add_filter( 'postbox_classes_dashboard_wp_dashboard_on_this_day', 'wp_dashboard_on_this_day_postbox_classes' );
-
-	wp_add_dashboard_widget(
-		'wp_dashboard_on_this_day',
-		__( 'On This Day' ),
-		'wp_dashboard_on_this_day'
-	);
-}
-
-/**
- * Hides the On This Day postbox when there are no posts to show.
- *
- * Adds the core `hidden` class so the widget stays registered — preserving its
- * Screen Options entry and user-customized position — while being hidden when
- * empty. A user can still reveal it via Screen Options, in which case the
- * placeholder message is shown.
- *
- * @since 7.1.0
- *
- * @param string[] $classes An array of postbox classes.
- * @return string[] Filtered postbox classes.
- */
-function wp_dashboard_on_this_day_postbox_classes( $classes ) {
-	if ( empty( wp_dashboard_on_this_day_get_posts() ) ) {
-		$classes[] = 'hidden';
-	}
-
-	return $classes;
-}
-
 /**
  * Renders the On This Day dashboard widget.
  *
@@ -60,8 +18,7 @@ function wp_dashboard_on_this_day() {
 	$posts = wp_dashboard_on_this_day_get_posts();
 
 	if ( empty( $posts ) ) {
-		// Placeholder shown when a user reveals the hidden widget via Screen
-		// Options on a day with no matching posts.
+		// Placeholder shown on a day with no matching posts in previous years.
 		echo '<p>' . esc_html__( 'No posts were published on this day in previous years.' ) . '</p>';
 		return;
 	}
diff --git a/src/wp-admin/includes/dashboard.php b/src/wp-admin/includes/dashboard.php
index 5fdbaf7a4fa40..a0c2a23189644 100644
--- a/src/wp-admin/includes/dashboard.php
+++ b/src/wp-admin/includes/dashboard.php
@@ -89,11 +89,11 @@ function wp_dashboard_setup() {
 	}
 
 	// On This Day.
-	if ( ! function_exists( 'wp_dashboard_on_this_day_setup' ) ) {
+	if ( ! function_exists( 'wp_dashboard_on_this_day' ) ) {
 		require_once ABSPATH . 'wp-admin/includes/dashboard-on-this-day.php';
 	}
 
-	wp_dashboard_on_this_day_setup();
+	wp_add_dashboard_widget( 'wp_dashboard_on_this_day', __( 'On This Day' ), 'wp_dashboard_on_this_day' );
 
 	// WordPress Events and News.
 	wp_add_dashboard_widget( 'dashboard_primary', __( 'WordPress Events and News' ), 'wp_dashboard_events_news' );
diff --git a/tests/phpunit/tests/admin/wpDashboardOnThisDay.php b/tests/phpunit/tests/admin/wpDashboardOnThisDay.php
index 471324f9648ec..ed6d7bfc18842 100644
--- a/tests/phpunit/tests/admin/wpDashboardOnThisDay.php
+++ b/tests/phpunit/tests/admin/wpDashboardOnThisDay.php
@@ -32,25 +32,6 @@ public static function wpTearDownAfterClass() {
 		self::delete_user( self::$other_user_id );
 	}
 
-	public function tear_down() {
-		unset( $GLOBALS['wp_meta_boxes']['dashboard'] );
-
-		parent::tear_down();
-	}
-
-	/**
-	 * Sets up the globals needed to register dashboard widgets.
-	 */
-	private function set_up_dashboard_screen() {
-		if ( ! function_exists( 'wp_add_dashboard_widget' ) ) {
-			require_once ABSPATH . 'wp-admin/includes/dashboard.php';
-		}
-
-		set_current_screen( 'dashboard' );
-
-		$GLOBALS['wp_meta_boxes']['dashboard'] = array();
-	}
-
 	/**
 	 * Creates a published post on the widget's prior-year calendar day.
 	 *
@@ -114,71 +95,6 @@ private static function get_date_query_clause( string $date ): array {
 		return _wp_dashboard_on_this_day_date_query_clause( new DateTimeImmutable( $date, wp_timezone() ) );
 	}
 
-	/**
-	 * @ticket 65116
-	 *
-	 * @covers ::wp_dashboard_on_this_day_setup
-	 */
-	public function test_setup_always_registers_widget_and_postbox_class_filter() {
-		$this->set_up_dashboard_screen();
-
-		wp_set_current_user( self::$user_id );
-
-		wp_dashboard_on_this_day_setup();
-
-		$dashboard_widgets = $GLOBALS['wp_meta_boxes']['dashboard']['normal']['core'] ?? array();
-
-		$this->assertArrayHasKey( 'wp_dashboard_on_this_day', $dashboard_widgets );
-		$this->assertSame( 'On This Day', $dashboard_widgets['wp_dashboard_on_this_day']['title'] );
-		$this->assertNotFalse(
-			has_filter(
-				'postbox_classes_dashboard_wp_dashboard_on_this_day',
-				'wp_dashboard_on_this_day_postbox_classes'
-			)
-		);
-	}
-
-	/**
-	 * @ticket 65116
-	 *
-	 * @covers ::wp_dashboard_on_this_day_postbox_classes
-	 */
-	public function test_postbox_classes_hides_widget_without_matching_posts() {
-		wp_set_current_user( self::$user_id );
-
-		$this->assertContains( 'hidden', wp_dashboard_on_this_day_postbox_classes( array( '' ) ) );
-	}
-
-	/**
-	 * @ticket 65116
-	 *
-	 * @covers ::wp_dashboard_on_this_day_postbox_classes
-	 */
-	public function test_postbox_classes_does_not_hide_widget_with_matching_posts() {
-		wp_set_current_user( self::$user_id );
-		$this->create_matching_post( self::$user_id );
-
-		$this->assertNotContains( 'hidden', wp_dashboard_on_this_day_postbox_classes( array( '' ) ) );
-	}
-
-	/**
-	 * @ticket 65116
-	 *
-	 * @covers ::wp_dashboard_on_this_day_setup
-	 */
-	public function test_setup_adds_dashboard_widget_with_matching_post_from_another_author() {
-		$this->set_up_dashboard_screen();
-
-		wp_set_current_user( self::$user_id );
-		$this->create_matching_post( self::$other_user_id );
-
-		wp_dashboard_on_this_day_setup();
-
-		$dashboard_widgets = $GLOBALS['wp_meta_boxes']['dashboard']['normal']['core'] ?? array();
-
-		$this->assertArrayHasKey( 'wp_dashboard_on_this_day', $dashboard_widgets );
-	}
-
 	/**
 	 * @ticket 65116
 	 *