Watanabe was born in Unzen on August 10, 1986. After graduating from Waseda University, he joined J1 League club Yokohama F. Marinos in 2009. In first season, he scored 13 goals and he was selected "J.League Rookie of the Year award". In 2012, he moved to FC Tokyo. He played for the club in 3 seasons. In 2015, he moved to Vissel Kobe. In August 2018, he moved to Gamba Osaka. In 2021, he moved to Yokohama FC.