diff --git a/packages/block-library/src/post-title/edit.js b/packages/block-library/src/post-title/edit.js
index 4a186276408daa..f6bba609907315 100644
--- a/packages/block-library/src/post-title/edit.js
+++ b/packages/block-library/src/post-title/edit.js
@@ -27,7 +27,7 @@ export default function PostTitleEdit( {
 	context: { postType, postId, queryId },
 	insertBlocksAfter,
 } ) {
-	const TagName = 'h' + level;
+	const TagName = level === 0 ? 'p' : `h${ level }`;
 	const isDescendentOfQueryLoop = Number.isFinite( queryId );
 	const userCanEdit = useSelect(
 		( select ) => {
diff --git a/packages/block-library/src/post-title/index.php b/packages/block-library/src/post-title/index.php
index f4a91a6891ea81..ed27f2e4158eb4 100644
--- a/packages/block-library/src/post-title/index.php
+++ b/packages/block-library/src/post-title/index.php
@@ -33,7 +33,7 @@ function render_block_core_post_title( $attributes, $content, $block ) {
 
 	$tag_name = 'h2';
 	if ( isset( $attributes['level'] ) ) {
-		$tag_name = 'h' . $attributes['level'];
+		$tag_name = 0 === $attributes['level'] ? 'p' : 'h' . (int) $attributes['level'];
 	}
 
 	if ( isset( $attributes['isLink'] ) && $attributes['isLink'] ) {