State Route 528 (SR 528) is a state highway in Snohomish County, Washington, located entirely within the city of Marysville. It spans 3.5 miles (5.6 km) from an interchange with Interstate 5 (I-5) in downtown Marysville to a junction with SR 9. The highway primarily functions as a commuter route and uses two local streets: 4th Street and 64th Street.