The 2020–21 Oklahoma City Thunder season was the 13th season of the franchise in Oklahoma City and the 55th in the National Basketball Association (NBA). This is the first season since 2014–15 without head coach Billy Donovan, as he mutually agreed to part ways with the Thunder on September 8, 2020, and 14 days later, went on to become the new head coach of the Chicago Bulls. For the first time since 2012–13, long-time players Steven Adams and André Roberson were not on the roster, as Adams was traded to the New Orleans Pelicans, and Roberson signed with the Brooklyn Nets.

The Oklahoma City Thunder played its inaugural season in the 2008–09 NBA season. It was the team's 1st season in Oklahoma City since the Seattle SuperSonics relocation was approved by league owners prior to settling a lawsuit. The team played at the Ford Center.