diff --git a/src/Templates/SingleProductTemplateCompatibility.php b/src/Templates/SingleProductTemplateCompatibility.php
index bb74c62bb89..5c2e9e4acdf 100644
--- a/src/Templates/SingleProductTemplateCompatibility.php
+++ b/src/Templates/SingleProductTemplateCompatibility.php
@@ -321,7 +321,7 @@ function( $carry, $item ) {
 				$carry['index'] = $carry['index'] + 1;
 				$block          = $item[0];
 
-				if ( 'core/template-part' === $block['blockName'] ) {
+				if ( 'core/template-part' === $block['blockName'] || self::is_custom_html( $block ) ) {
 					$carry['template'][] = $block;
 					return $carry;
 				}
@@ -433,9 +433,6 @@ function( $carry, $block ) {
 					$carry[] = array( $block );
 					return $carry;
 				}
-				if ( empty( $block['blockName'] ) ) {
-					return $carry;
-				}
 				$last_element_index = count( $carry ) - 1;
 				if ( isset( $carry[ $last_element_index ][0]['blockName'] ) && 'core/template-part' !== $carry[ $last_element_index ][0]['blockName'] ) {
 					$carry[ $last_element_index ][] = $block;
@@ -468,6 +465,16 @@ private function inject_hooks_after_the_wrapper( $block_content, $hooks ) {
 			$closing_tag_position + 1,
 			0
 		);
+	}
 
+
+	/**
+	 * Plain custom HTML block is parsed as block with an empty blockName with a filled innerHTML.
+	 *
+	 * @param array $block Parse block.
+	 * @return bool
+	 */
+	private static function is_custom_html( $block ) {
+		return empty( $block['blockName'] ) && ! empty( $block['innerHTML'] );
 	}
 }
diff --git a/tests/php/Templates/SingleProductTemplateCompatibilityTests.php b/tests/php/Templates/SingleProductTemplateCompatibilityTests.php
index fd87ba6c5f1..77ac60e13e0 100644
--- a/tests/php/Templates/SingleProductTemplateCompatibilityTests.php
+++ b/tests/php/Templates/SingleProductTemplateCompatibilityTests.php
@@ -327,4 +327,41 @@ public function test_add_compatibility_layer_with_multiple_blocks_related_to_the
 
 		$this->assertEquals( $result_without_withespace, $expected_single_product_template_without_whitespace, '' );
 	}
+
+	/**
+	 * Test that the Single Product Template is wrapped in a div with the correct class if it contains a block related to the Single Product Template and custom HTML isn't removed.
+	 */
+	public function test_add_compatibility_layer_if_contains_single_product_blocks_and_custom_HTML_not_removed() {
+
+		$default_single_product_template = '
+		<!-- wp:template-part {"slug":"header","theme":"twentytwentythree","tagName":"header"} /-->
+		<span>Custom HTML</span>
+		<!-- wp:group {"layout":{"inherit":true,"type":"constrained"}} -->
+		<div class="wp-block-group">
+		   <!-- wp:woocommerce/product-image-gallery /-->
+		</div>
+		<!-- /wp:group -->
+		<!-- wp:template-part {"slug":"footer","theme":"twentytwentythree","tagName":"footer"} /-->';
+
+		$expected_single_product_template = '
+		<!-- wp:template-part {"slug":"header","theme":"twentytwentythree","tagName":"header"} /-->
+		<span>Custom HTML</span>
+		<!-- wp:group {"className":"woocommerce product", "__wooCommerceIsFirstBlock":true,"__wooCommerceIsLastBlock":true} -->
+		<div class="wp-block-group woocommerce product">
+		   <!-- wp:group {"layout":{"inherit":true,"type":"constrained"}} -->
+		   <div class="wp-block-group">
+			  <!-- wp:woocommerce/product-image-gallery /-->
+		   </div>
+		   <!-- /wp:group -->
+		</div>
+		<!-- /wp:group -->
+		<!-- wp:template-part {"slug":"footer","theme":"twentytwentythree","tagName":"footer"} /-->';
+
+		$result = SingleProductTemplateCompatibility::add_compatibility_layer( $default_single_product_template );
+
+		$result_without_withespace                           = preg_replace( '/\s+/', '', $result );
+		$expected_single_product_template_without_whitespace = preg_replace( '/\s+/', '', $expected_single_product_template );
+
+		$this->assertEquals( $result_without_withespace, $expected_single_product_template_without_whitespace, '' );
+	}
 }