The 2021 NASCAR Cup Series was the 73rd season for NASCAR professional stock car racing in the United States and the 50th season for the modern era Cup Series. The season started at Daytona International Speedway with the Busch Clash, where it was the first year that the non-points event was run on the track's road course layout instead of the oval. That race was followed by the Bluegreen Vacations Duel qualifying races, and the 63rd running of the Daytona 500, the first points race of the season. The regular season also ended at Daytona with the 2021 Coke Zero Sugar 400 on August 28, where Kyle Larson won the Regular Season Championship. Following the 2021 Xfinity 500 at Martinsville Speedway on October 31, Chevrolet claimed its 40th Manufacturer's Championship and its first since 2015. The NASCAR playoffs ended with the NASCAR Cup Series Championship Race at Phoenix Raceway on November 7 with Larson earning his first Cup Series championship after a 10-win season.

The Busch Light Clash is an annual non-championship pre-season NASCAR Cup Series exhibition event held in February before the season-opening Daytona 500. The event was held each year at Daytona International Speedway from the race's inception in 1979 until 2021, after which it was moved to the Los Angeles Memorial Coliseum beginning in 2022. Previously at Daytona, the race, along with the ARCA Menards Series' season-opening BRANDT 200, served as the kickoff events for Daytona Speedweeks. The event is one of two non-points races on the Cup Series schedule, the other being the NASCAR All-Star Race.