The 2021 Reese's 150 was the 20th and final stock car race of the 2021 ARCA Menards Series, and the 21st iteration of the event. The race was held on Saturday, October 23, 2021 in Kansas City, Kansas at Kansas Speedway, a 1.500 miles (2.414 km) permanent paved oval-shaped racetrack. The race took 102 laps to complete due to an overtime finish. On the final restart on lap 101, Nick Sanchez of Rev Racing would take the lead to win his first career ARCA Menards Series win and his only win of the season. Meanwhile, Ty Gibbs of Joe Gibbs Racing, who finished 2nd, would win the 2021 ARCA Menards Series championship after taking the green flag, who won by 37 points over Corey Heim. To fill out the podium, Rajah Caruth of Rev Racing would finish third.