diff --git a/lib/register.php b/lib/register.php
index 5e8cdbd00d238..1795c1036fb1f 100644
--- a/lib/register.php
+++ b/lib/register.php
@@ -365,7 +365,7 @@ function has_blocks( $post = null ) {
  * @see gutenberg_parse_blocks()
  *
  * @since 0.5.0
- * @deprecated 3.6.0 Use has_block()
+ * @deprecated 3.6.0 Use has_blocks()
  *
  * @param object $post Post.
  * @return bool  Whether the post has blocks.
@@ -384,7 +384,7 @@ function gutenberg_post_has_blocks( $post ) {
  * @see gutenberg_parse_blocks()
  *
  * @since 1.6.0
- * @deprecated 3.6.0 Use has_block()
+ * @deprecated 3.6.0 Use has_blocks()
  *
  * @param string $content Content to test.
  * @return bool Whether the content contains blocks.
@@ -394,6 +394,33 @@ function gutenberg_content_has_blocks( $content ) {
 	return has_blocks( $content );
 }
 
+/**
+ * Determine whether a $post or a string contains a specific block type.
+ * This test optimizes for performance rather than strict accuracy, detecting
+ * the block type exists but not validating its structure.
+ * For strict accuracy, you should use the block parser on post content.
+ *
+ * @since 3.6.0
+ *
+ * @param string                  $block_type Full Block type to look for.
+ * @param int|string|WP_Post|null $post Optional. Post content, post ID, or post object. Defaults to global $post.
+ * @return bool Whether the post content contains the specified block.
+ */
+function has_block( $block_type, $post = null ) {
+	if ( ! has_blocks( $post ) ) {
+		return false;
+	}
+
+	if ( ! is_string( $post ) ) {
+		$wp_post = get_post( $post );
+		if ( $wp_post instanceof WP_Post ) {
+			$post = $wp_post->post_content;
+		}
+	}
+
+	return false !== strpos( $post, '<!-- wp:' . $block_type . ' ' );
+}
+
 /**
  * Returns the current version of the block format that the content string is using.
  *
diff --git a/phpunit/class-block-type-test.php b/phpunit/class-block-type-test.php
index f9e5f032ec36c..fb2e07d78e4da 100644
--- a/phpunit/class-block-type-test.php
+++ b/phpunit/class-block-type-test.php
@@ -9,6 +9,50 @@
  * Tests for WP_Block_Type
  */
 class Block_Type_Test extends WP_UnitTestCase {
+	function setUp() {
+		parent::setUp();
+	}
+
+	/**
+	 * Editor user ID.
+	 *
+	 * @var int
+	 */
+	protected static $editor_user_id;
+
+	/**
+	 * ID for a post containing blocks.
+	 *
+	 * @var int
+	 */
+	protected static $post_with_blocks;
+
+	/**
+	 * ID for a post without blocks.
+	 *
+	 * @var int
+	 */
+	protected static $post_without_blocks;
+
+	/**
+	 * Set up before class.
+	 */
+	public static function wpSetUpBeforeClass() {
+		self::$editor_user_id = self::factory()->user->create( array(
+			'role' => 'editor',
+		) );
+
+		self::$post_with_blocks = self::factory()->post->create( array(
+			'post_title'   => 'Example',
+			'post_content' => "<!-- wp:core/text {\"dropCap\":true} -->\n<p class=\"has-drop-cap\">Tester</p>\n<!-- /wp:core/text -->",
+		) );
+
+		self::$post_without_blocks = self::factory()->post->create( array(
+			'post_title'   => 'Example',
+			'post_content' => 'Tester',
+		) );
+	}
+
 	function test_set_props() {
 		$name = 'core/dummy';
 		$args = array(
@@ -112,6 +156,75 @@ function test_prepare_attributes() {
 		), $prepared_attributes );
 	}
 
+	function test_has_block_with_mixed_content() {
+		$mixed_post_content = 'before' .
+		'<!-- wp:core/dummy --><!-- /wp:core/dummy -->' .
+		'<!-- wp:core/dummy_atts {"value":"b1"} --><!-- /wp:core/dummy_atts -->' .
+		'<!-- wp:core/dummy-child -->
+		<p>testing the test</p>
+		<!-- /wp:core/dummy-child -->' .
+		'between' .
+		'<!-- wp:core/self-close-dummy /-->' .
+		'<!-- wp:custom/dummy {"value":"b2"} /-->' .
+		'after';
+
+		$this->assertTrue( has_block( 'core/dummy', $mixed_post_content ) );
+
+		$this->assertTrue( has_block( 'core/dummy_atts', $mixed_post_content ) );
+
+		$this->assertTrue( has_block( 'core/dummy-child', $mixed_post_content ) );
+
+		$this->assertTrue( has_block( 'core/self-close-dummy', $mixed_post_content ) );
+
+		$this->assertTrue( has_block( 'custom/dummy', $mixed_post_content ) );
+
+		// checking for a partial block name should fail.
+		$this->assertFalse( has_block( 'core/dumm', $mixed_post_content ) );
+
+		// checking for a wrong namespace should fail.
+		$this->assertFalse( has_block( 'custom/dummy_atts', $mixed_post_content ) );
+
+		// checking for namespace only should not work. Or maybe ... ?
+		$this->assertFalse( has_block( 'core', $mixed_post_content ) );
+	}
+
+	function test_has_block_with_invalid_content() {
+		// some content with invalid HMTL comments and a single valid block.
+		$invalid_content = 'before' .
+		'<!- - wp:core/weird-space --><!-- /wp:core/weird-space -->' .
+		'<!--wp:core/untrimmed-left --><!-- /wp:core/untrimmed -->' .
+		'<!-- wp:core/dummy --><!-- /wp:core/dummy -->' .
+		'<!-- wp:core/untrimmed-right--><!-- /wp:core/untrimmed2 -->' .
+		'after';
+
+		$this->assertFalse( has_block( 'core/text', self::$post_without_blocks ) );
+
+		$this->assertFalse( has_block( 'core/weird-space', $invalid_content ) );
+
+		$this->assertFalse( has_block( 'core/untrimmed-left', $invalid_content ) );
+
+		$this->assertFalse( has_block( 'core/untrimmed-right', $invalid_content ) );
+
+		$this->assertTrue( has_block( 'core/dummy', $invalid_content ) );
+	}
+
+	function test_post_has_block() {
+		// should fail for a non-existent block `custom/dummy`.
+		$this->assertFalse( has_block( 'custom/dummy', self::$post_with_blocks ) );
+
+		// this functions should not work without the second param until the $post global is set.
+		$this->assertFalse( has_block( 'core/text' ) );
+		$this->assertFalse( has_block( 'core/dummy' ) );
+
+		global $post;
+		$post = get_post( self::$post_with_blocks );
+
+		// check if the function correctly detects content from the $post global.
+		$this->assertTrue( has_block( 'core/text' ) );
+		// even if it detects a proper $post global it should still be false for a missing block.
+		$this->assertFalse( has_block( 'core/dummy' ) );
+	}
+
 	function render_dummy_block( $attributes ) {
 		return json_encode( $attributes );
 	}