Shunsuke Mitsui (born 20 May 2002) is a Japanese tennis player.
Mitsui has a career high ATP singles ranking of No. 518 achieved on 9 February 2026 and a career high ATP doubles ranking of No. 453 achieved on 21 August 2023.
Mitsui has won one ATP Challenger doubles title at the 2025 Champaign Challenger.
Mitsui played college tennis at Tennessee.