Watanabe was born in Fujieda on September 10, 1972. After graduating from Chuo University, he joined Kashiwa Reysol in 1995. He played as regular player from first season. The club won the champions at 1999 J.League Cup. At the final, he scored a tie goal in the 89th minute and he was selected MVP award. The club also won the 3rd place in 1999 and 2000 J1 League. He retired end of 2004 season.