The 2020–21 Big 12 men's basketball season began with practices in October 2020, followed by the start of the 2020–21 NCAA Division I men's basketball season in November.

Regular season conference play began in December 2020 and concluded in March 2021.

The Big 12 tournament was held from March 11–14, 2021 and was played at the T-Mobile Center in Kansas City, Missouri.

There were no head coaching changes following the 2019–20 Big 12 Conference men's basketball season.

To earn "consensus" status, a player must win honors from a majority of the following teams: the Associated Press, the USBWA, Sporting News, and the National Association of Basketball Coaches.