diff --git a/src/wp-includes/class-wp-block-patterns-registry.php b/src/wp-includes/class-wp-block-patterns-registry.php
index 56bcd8fd7785c..454a7c4a64249 100644
--- a/src/wp-includes/class-wp-block-patterns-registry.php
+++ b/src/wp-includes/class-wp-block-patterns-registry.php
@@ -115,6 +115,12 @@ public function register( $pattern_name, $pattern_properties ) {
 			array( 'name' => $pattern_name )
 		);
 
+		// Set `theme` attribute in Template Part blocks, and insert hooked blocks.
+		$blocks               = parse_blocks( $pattern['content'] );
+		$before_block_visitor = make_before_block_visitor( $pattern );
+		$after_block_visitor  = make_after_block_visitor( $pattern );
+		$pattern['content']   = traverse_and_serialize_blocks( $blocks, $before_block_visitor, $after_block_visitor );
+
 		$this->registered_patterns[ $pattern_name ] = $pattern;
 
 		// If the pattern is registered inside an action other than `init`, store it
@@ -165,13 +171,7 @@ public function get_registered( $pattern_name ) {
 			return null;
 		}
 
-		$pattern              = $this->registered_patterns[ $pattern_name ];
-		$blocks               = parse_blocks( $pattern['content'] );
-		$before_block_visitor = make_before_block_visitor( $pattern );
-		$after_block_visitor  = make_after_block_visitor( $pattern );
-		$pattern['content']   = traverse_and_serialize_blocks( $blocks, $before_block_visitor, $after_block_visitor );
-
-		return $pattern;
+		return $this->registered_patterns[ $pattern_name ];
 	}
 
 	/**
@@ -184,19 +184,11 @@ public function get_registered( $pattern_name ) {
 	 *                 and per style.
 	 */
 	public function get_all_registered( $outside_init_only = false ) {
-		$patterns = array_values(
+		return array_values(
 			$outside_init_only
 				? $this->registered_patterns_outside_init
 				: $this->registered_patterns
 		);
-
-		foreach ( $patterns as $index => $pattern ) {
-			$blocks                        = parse_blocks( $pattern['content'] );
-			$before_block_visitor          = make_before_block_visitor( $pattern );
-			$after_block_visitor           = make_after_block_visitor( $pattern );
-			$patterns[ $index ]['content'] = traverse_and_serialize_blocks( $blocks, $before_block_visitor, $after_block_visitor );
-		}
-		return $patterns;
 	}
 
 	/**