diff --git a/src/wp-includes/rest-api.php b/src/wp-includes/rest-api.php
index 6c2e7b693b..cc600789f0 100644
--- a/src/wp-includes/rest-api.php
+++ b/src/wp-includes/rest-api.php
@@ -1382,6 +1382,14 @@ function rest_validate_value_from_schema( $value, $args, $param = '' ) {
 				)
 			);
 		}
+
+		if ( isset( $args['pattern'] ) ) {
+			$pattern = str_replace( '#', '\\#', $args['pattern'] );
+			if ( ! preg_match( '#' . $pattern . '#u', $value ) ) {
+				/* translators: 1: Parameter, 2: Pattern. */
+				return new WP_Error( 'rest_invalid_pattern', sprintf( __( '%1$s does not match pattern %2$s.' ), $param, $args['pattern'] ) );
+			}
+		}
 	}
 
 	if ( isset( $args['format'] ) ) {
diff --git a/tests/phpunit/tests/rest-api/rest-schema-validation.php b/tests/phpunit/tests/rest-api/rest-schema-validation.php
index a46b1f0de0..09dd271a23 100644
--- a/tests/phpunit/tests/rest-api/rest-schema-validation.php
+++ b/tests/phpunit/tests/rest-api/rest-schema-validation.php
@@ -727,4 +727,43 @@ class WP_Test_REST_Schema_Validation extends WP_UnitTestCase {
 			),
 		);
 	}
+
+	/**
+	 * @ticket 44949
+	 */
+	public function test_string_pattern() {
+		$schema = array(
+			'type'    => 'string',
+			'pattern' => '^a*$',
+		);
+
+		$this->assertTrue( rest_validate_value_from_schema( 'a', $schema ) );
+		$this->assertWPError( rest_validate_value_from_schema( 'b', $schema ) );
+	}
+
+	/**
+	 * @ticket 44949
+	 */
+	public function test_string_pattern_with_escaped_delimiter() {
+		$schema = array(
+			'type'    => 'string',
+			'pattern' => '#[0-9]+',
+		);
+
+		$this->assertTrue( rest_validate_value_from_schema( '#123', $schema ) );
+		$this->assertWPError( rest_validate_value_from_schema( '#abc', $schema ) );
+	}
+
+	/**
+	 * @ticket 44949
+	 */
+	public function test_string_pattern_with_utf8() {
+		$schema = array(
+			'type'    => 'string',
+			'pattern' => '^â{1}$',
+		);
+
+		$this->assertTrue( rest_validate_value_from_schema( 'â', $schema ) );
+		$this->assertWPError( rest_validate_value_from_schema( 'ââ', $schema ) );
+	}
 }