diff --git a/src/wp-includes/class-wp-block-supports.php b/src/wp-includes/class-wp-block-supports.php
index ec5bc9c8d6846..a752d413a810a 100644
--- a/src/wp-includes/class-wp-block-supports.php
+++ b/src/wp-includes/class-wp-block-supports.php
@@ -121,7 +121,7 @@ public function apply_block_supports() {
 
 			if ( ! empty( $new_attributes ) ) {
 				foreach ( $new_attributes as $attribute_name => $attribute_value ) {
-					if ( empty( $output[ $attribute_name ] ) ) {
+					if ( ! array_key_exists( $attribute_name, $output ) || '' === (string) $output[ $attribute_name ] ) {
 						$output[ $attribute_name ] = $attribute_value;
 					} else {
 						$output[ $attribute_name ] .= " $attribute_value";
@@ -184,26 +184,32 @@ function get_block_wrapper_attributes( $extra_attributes = array() ) {
 	$attributes_to_merge = array( 'style', 'class', 'id', 'aria-label' );
 	$attributes          = array();
 	foreach ( $attributes_to_merge as $attribute_name ) {
-		if ( empty( $new_attributes[ $attribute_name ] ) && empty( $extra_attributes[ $attribute_name ] ) ) {
+		$new_value   = array_key_exists( $attribute_name, $new_attributes ) ? (string) $new_attributes[ $attribute_name ] : '';
+		$extra_value = array_key_exists( $attribute_name, $extra_attributes ) ? (string) $extra_attributes[ $attribute_name ] : '';
+
+		if ( '' === $new_value && '' === $extra_value ) {
 			continue;
 		}
 
-		if ( empty( $new_attributes[ $attribute_name ] ) ) {
-			$attributes[ $attribute_name ] = $extra_attributes[ $attribute_name ];
+		if ( '' === $new_value ) {
+			$attributes[ $attribute_name ] = $extra_value;
 			continue;
 		}
 
-		if ( empty( $extra_attributes[ $attribute_name ] ) ) {
-			$attributes[ $attribute_name ] = $new_attributes[ $attribute_name ];
+		if ( '' === $extra_value ) {
+			$attributes[ $attribute_name ] = $new_value;
 			continue;
 		}
 
-		$attributes[ $attribute_name ] = $extra_attributes[ $attribute_name ] . ' ' . $new_attributes[ $attribute_name ];
+		$attributes[ $attribute_name ] = $extra_value . ' ' . $new_value;
 	}
 
 	foreach ( $extra_attributes as $attribute_name => $value ) {
 		if ( ! in_array( $attribute_name, $attributes_to_merge, true ) ) {
-			$attributes[ $attribute_name ] = $value;
+			$string_value = (string) $value;
+			if ( '' !== $string_value ) {
+				$attributes[ $attribute_name ] = $string_value;
+			}
 		}
 	}
 
diff --git a/tests/phpunit/tests/blocks/getBlockWrapperAttributes.php b/tests/phpunit/tests/blocks/getBlockWrapperAttributes.php
new file mode 100644
index 0000000000000..c3c31cd92e877
--- /dev/null
+++ b/tests/phpunit/tests/blocks/getBlockWrapperAttributes.php
@@ -0,0 +1,121 @@
+<?php
+/**
+ * Tests for get_block_wrapper_attributes function.
+ *
+ * @package WordPress
+ * @subpackage Blocks
+ *
+ * @since 7.0.0
+ *
+ * @group blocks
+ * @covers ::get_block_wrapper_attributes
+ */
+class Tests_Blocks_GetBlockWrapperAttributes extends WP_UnitTestCase {
+
+	/**
+	 * Tear down after each test.
+	 *
+	 * @since 7.0.0
+	 */
+	public function tear_down() {
+		$registry = WP_Block_Type_Registry::get_instance();
+		if ( $registry->is_registered( 'core/example' ) ) {
+			$registry->unregister( 'core/example' );
+		}
+		if ( $registry->is_registered( 'core/example' ) ) {
+			$registry->unregister( 'core/example' );
+		}
+
+		parent::tear_down();
+	}
+
+	/**
+	 * @ticket 64452
+	 */
+	public function test_preserves_zero_values() {
+		WP_Block_Supports::init();
+		register_block_type(
+			'core/example',
+			array(
+				'supports' => array(
+					'customClassName' => true,
+					'ariaLabel'       => true,
+				),
+			)
+		);
+		WP_Block_Supports::$block_to_render = array(
+			'blockName' => 'core/example',
+			'attrs'     => array(
+				'className' => '0',
+				'ariaLabel' => 0,
+			),
+		);
+
+		$result = get_block_wrapper_attributes();
+		$this->assertSame( 'class="0 wp-block-example" aria-label="0"', $result );
+	}
+
+	/**
+	 * @ticket 64452
+	 */
+	public function test_preserves_zero_values_from_extra_attributes() {
+		WP_Block_Supports::init();
+		register_block_type( 'core/example' );
+		WP_Block_Supports::$block_to_render = array( 'blockName' => 'core/example' );
+
+		$result = get_block_wrapper_attributes(
+			array(
+				'class'      => '0',
+				'aria-label' => 0,
+				'data-foo'   => 0,
+				'data-var'   => '0',
+			)
+		);
+		$this->assertSame( 'class="0 wp-block-example" aria-label="0" data-foo="0" data-var="0"', $result );
+	}
+
+	/**
+	 * @ticket 64452
+	 */
+	public function test_excludes_falsy_values_except_zero() {
+		WP_Block_Supports::init();
+		register_block_type(
+			'core/example',
+			array(
+				'supports' => array(
+					'customClassName' => true,
+					'ariaLabel'       => true,
+				),
+			)
+		);
+		WP_Block_Supports::$block_to_render = array(
+			'blockName' => 'core/example',
+			'attrs'     => array(
+				'className' => false,
+				'ariaLabel' => null,
+			),
+		);
+
+		$result = get_block_wrapper_attributes();
+		$this->assertSame( 'class="wp-block-example"', $result );
+	}
+
+	/**
+	 * @ticket 64452
+	 */
+	public function test_excludes_falsy_values_except_zero_from_extra_attributes() {
+		WP_Block_Supports::init();
+		register_block_type( 'core/example' );
+		WP_Block_Supports::$block_to_render = array( 'blockName' => 'core/example' );
+
+		$result = get_block_wrapper_attributes(
+			array(
+				'class'      => false,
+				'aria-label' => null,
+				'data-var'   => false,
+				'data-baz'   => null,
+			)
+		);
+		$this->assertSame( 'class="wp-block-example"', $result );
+	}
+}