The 2021 Phillips 66 Big 12 men's basketball tournament was a postseason men's basketball tournament for the Big 12 Conference.

It was played from March 10 to 13, in Kansas City, Missouri at the T-Mobile Center.

[1] The winner received the conference's automatic bid to the 2021 NCAA tournament.

Texas became the first school that was not a member of the Big Eight Conference to win the tournament.

Teams were seeded by record within the conference, with a tiebreaker system to seed teams with identical conference records.