Larson, 29, is the only Asian American to race full-time in NASCAR, driving the No. 5 Chevrolet for Hendrick Motorsports. He made the playoffs 2016-2019 while driving for Chip Ganassi Racing but sat out last year's event after NASCAR suspended him for making a racial slur.
Hendrick Motorsports added Larson to its team once he was reinstated and he had his first win for the team in March at Las Vegas Motor Speedway.
Four drivers were competing for the championship among a field of 39 at the one-mile oval track.
Larson crossed the line ahead of teammate Chase Elliott, who won the Cup Series Championship in 2020 and whose father, Bill Elliott, is a NASCAR Hall of Fame inductee. Elliott drives a No. 9 Chevrolet for Hendrick Motorsports, the same car number as his father.
Hendrick Motorsports was up against Joe Gibbs Racing in the final, with Denny Hamlin -- the longest-tenured driver at Joe Gibbs Racing -- driving the team's No. 11 Toyota.
Martin Truex Jr. drove the No. 19 Toyota for Joe Gibbs Racing and last won the Cup Series in 2017. He was second over the finish line Sunday, behind Larson.
Competing for the best finish
The NASCAR Cup Series is the stock car racing organization's premier competition. After a 26-race regular season, the 16 drivers with the most points compete in a 10-race elimination playoff.
The final four drivers -- the Championship 4 -- compete for the best finish in the championship race, with the winner taking the Bill France Cup, named for NASCAR's founder.
NASCAR -- The National Association for Stock Car Auto Racing -- was established in 1947.
Stock cars are large, late-model sedans that have been built especially for racing. The stock car's large engine allows it to reach speeds exceeding 200 miles per hour.
NASCAR runs three national series: the NASCAR Cup Series, NASCAR Xfinity Series and the NASCAR Camping World Truck Series for modified pickup trucks.