The 2018 NASCAR Xfinity Series was the 37th season of the NASCAR Xfinity Series, a stock car racing series sanctioned by NASCAR in the United States. William Byron won the 2017 championship with JR Motorsports, but moved up to the Monster Energy NASCAR Cup Series. Tyler Reddick, who replaced Byron in the No. 9 JR Motorsports Chevrolet Camaro SS, won the drivers' championship. Stewart-Haas Racing with Biagi-DenBeste won the owners' championship.