The 2021 Big West Conference men's basketball tournament was the postseason men's basketball tournament for the Big West Conference of the 2020-21 NCAA Division I men's basketball season.
It was held from March 9–13, 2021 at the Michelob Ultra Arena in Paradise, Nevada.
The winner received the conference's automatic bid to the 2021 NCAA tournament.
UC San Diego was ineligible for this year's tournament, as they were in the first year of the four-year transition required for teams transferring to Division I from Division II.
Teams were seeded by record within the conference, with a tiebreaker system to seed teams with identical conference records.