diff --git a/packages/block-library/src/navigation/index.php b/packages/block-library/src/navigation/index.php
index fcc4c9198d4cc0..86023738370090 100644
--- a/packages/block-library/src/navigation/index.php
+++ b/packages/block-library/src/navigation/index.php
@@ -697,14 +697,10 @@ private static function get_responsive_container_markup( $attributes, $inner_blo
 		if ( ! empty( $attributes['overlay'] ) ) {
 			// Get blocks from the overlay template part.
 			$overlay_blocks = static::get_overlay_blocks_from_template_part( $attributes['overlay'], $attributes );
-			// Check if overlay contains a navigation-overlay-close block.
-			$has_custom_overlay_close_block = block_core_navigation_block_tree_has_block_type(
-				$overlay_blocks,
-				'core/navigation-overlay-close',
-				array( 'core/navigation' ) // Skip navigation blocks, as they cannot contain an overlay close block
-			);
 			// Render template part blocks directly without navigation container wrapper.
 			$overlay_blocks_html = static::get_template_part_blocks_html( $overlay_blocks );
+			// Check if overlay contains a navigation-overlay-close block (detect in rendered HTML so it works with patterns).
+			$has_custom_overlay_close_block = block_core_navigation_overlay_html_has_close_block( $overlay_blocks_html );
 			// Add Interactivity API directives to the overlay close block if present.
 			if ( $has_custom_overlay_close_block && $is_interactive ) {
 				$tags                = new WP_HTML_Tag_Processor( $overlay_blocks_html );
@@ -1094,6 +1090,28 @@ function block_core_navigation_get_inner_blocks_from_unstable_location( $attribu
 	}
 }
 
+/**
+ * Checks if the overlay HTML contains a navigation-overlay-close block.
+ *
+ * Uses WP_HTML_Tag_Processor to detect the close button in rendered output,
+ * so it works when the overlay uses patterns (pattern content is rendered at
+ * output time, not in the block tree).
+ *
+ * @since 7.0.0
+ *
+ * @param string $html The rendered overlay HTML.
+ * @return bool True if a close button element is found.
+ */
+function block_core_navigation_overlay_html_has_close_block( $html ) {
+	$tags = new WP_HTML_Tag_Processor( $html );
+	return $tags->next_tag(
+		array(
+			'tag_name'   => 'BUTTON',
+			'class_name' => 'wp-block-navigation-overlay-close',
+		)
+	);
+}
+
 /**
  * Add Interactivity API directives to the navigation-overlay-close block
  * markup using the Tag Processor.
diff --git a/phpunit/blocks/class-wp-navigation-block-renderer-test.php b/phpunit/blocks/class-wp-navigation-block-renderer-test.php
index e6f7c1dd5144fb..fc81a57f659194 100644
--- a/phpunit/blocks/class-wp-navigation-block-renderer-test.php
+++ b/phpunit/blocks/class-wp-navigation-block-renderer-test.php
@@ -253,6 +253,98 @@ public function test_gutenberg_block_core_navigation_block_tree_has_block_type_r
 		$this->assertFalse( $result );
 	}
 
+	/**
+	 * Test that gutenberg_block_core_navigation_overlay_html_has_close_block returns true when HTML contains the close button element.
+	 *
+	 * @group navigation-renderer
+	 *
+	 * @covers ::gutenberg_block_core_navigation_overlay_html_has_close_block
+	 */
+	public function test_gutenberg_block_core_navigation_overlay_html_has_close_block_returns_true_when_close_button_present() {
+		$html   = '<div class="wp-block-group"><button class="wp-block-navigation-overlay-close" type="button">Close</button></div>';
+		$result = gutenberg_block_core_navigation_overlay_html_has_close_block( $html );
+		$this->assertTrue( $result );
+	}
+
+	/**
+	 * Test that gutenberg_block_core_navigation_overlay_html_has_close_block returns false when HTML does not contain the close button.
+	 *
+	 * @group navigation-renderer
+	 *
+	 * @covers ::gutenberg_block_core_navigation_overlay_html_has_close_block
+	 */
+	public function test_gutenberg_block_core_navigation_overlay_html_has_close_block_returns_false_when_absent() {
+		$html   = '<div class="wp-block-group"><p>No close button here</p></div>';
+		$result = gutenberg_block_core_navigation_overlay_html_has_close_block( $html );
+		$this->assertFalse( $result );
+	}
+
+	/**
+	 * Test that gutenberg_block_core_navigation_overlay_html_has_close_block returns false when class string appears only in text content.
+	 *
+	 * @group navigation-renderer
+	 *
+	 * @covers ::gutenberg_block_core_navigation_overlay_html_has_close_block
+	 */
+	public function test_gutenberg_block_core_navigation_overlay_html_has_close_block_returns_false_when_class_in_text_only() {
+		$html   = '<p>Use the wp-block-navigation-overlay-close button to close</p>';
+		$result = gutenberg_block_core_navigation_overlay_html_has_close_block( $html );
+		$this->assertFalse( $result );
+	}
+
+	/**
+	 * Test that gutenberg_block_core_navigation_overlay_html_has_close_block finds nested close button.
+	 *
+	 * @group navigation-renderer
+	 *
+	 * @covers ::gutenberg_block_core_navigation_overlay_html_has_close_block
+	 */
+	public function test_block_core_navigation_overlay_html_has_close_block_finds_nested_close_button() {
+		$html   = '<div class="wp-block-group"><div class="wp-block-group"><button class="wp-block-navigation-overlay-close" type="button" aria-label="Close"><svg>...</svg></button></div></div>';
+		$result = gutenberg_block_core_navigation_overlay_html_has_close_block( $html );
+		$this->assertTrue( $result );
+	}
+
+	/**
+	 * Test that gutenberg_block_core_navigation_overlay_html_has_close_block detects close block when overlay content is a pattern.
+	 *
+	 * Simulates the bug scenario: template part contains wp:pattern, pattern renders its content including the close block.
+	 *
+	 * @group navigation-renderer
+	 *
+	 * @covers ::gutenberg_block_core_navigation_overlay_html_has_close_block
+	 */
+	public function test_block_core_navigation_overlay_html_has_close_block_detects_close_in_pattern_output() {
+		register_block_pattern(
+			'test/navigation-overlay-pattern',
+			array(
+				'title'       => 'Navigation Overlay Pattern',
+				'content'     => '<!-- wp:group --><div class="wp-block-group"><!-- wp:navigation-overlay-close /--></div><!-- /wp:group -->',
+				'description' => 'Pattern containing navigation-overlay-close (simulates overlay template part using pattern).',
+				'categories'  => array( 'navigation' ),
+			)
+		);
+
+		try {
+			// Simulate overlay template part content: just a pattern block (unresolved in block tree).
+			$parsed_blocks = parse_blocks( '<!-- wp:pattern {"slug":"test/navigation-overlay-pattern"} /-->' );
+			$blocks        = new WP_Block_List( $parsed_blocks, array() );
+
+			// Render blocks (pattern block's render_callback outputs pattern content).
+			$html = '';
+			foreach ( $blocks as $block ) {
+				$html .= $block->render();
+			}
+
+			$this->assertTrue(
+				gutenberg_block_core_navigation_overlay_html_has_close_block( $html ),
+				'Close block should be detected in rendered pattern output (fixes #76567).'
+			);
+		} finally {
+			unregister_block_pattern( 'test/navigation-overlay-pattern' );
+		}
+	}
+
 	/**
 	 * Test that gutenberg_block_core_navigation_block_tree_has_block_type skips searching inside specified block types.
 	 *