The 24-year-old Byron from Charlotte, North Carolina, led a race-high 212 of 403 and fended off Joey Logano during an overtime shootout to repeat as a Cup winner at the Paperclip-shaped short track.
The 2020 NASCAR Xfinity Series champion commenced his first full-time campaign in the Cup Series by becoming the 41st different winner of the Great American Race.
The Elk Grove, California, native benefitted from a late run-in involving teammate Elliott and Harvick to win for the sixth time in 2021 at Thunder Valley.