Seita Watanabe (渡邉 聖太, Watanabe Seita, born 25 December 2000) is a Japanese tennis player who specializes in doubles.

He has a career high ATP doubles ranking of world No.

[1] Watanabe made his ATP main draw debut at the 2023 Japan Open Tennis Championships after entering the doubles main draw with Takeru Yuzuki as lucky losers.

[citation needed] Watanabe made his Grand Slam main draw debut at the 2025 Australian Open after entering the doubles main draw with Takeru Yuzuki as a wildcard pair.

[2] This biographical article relating to Japanese tennis is a stub.