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 reigning NASCAR Cup Series champion led four times for 28 of 200 laps and fended off the field in a four-lap shootout to claim his second victory at Auto Club Speedway.
The Tucson, Arizona, native spoiled the Playoff battle by claiming his first win at the Paperclip track amid a controversial incident with Denny Hamlin.
The High Point, North Carolina, native claimed his third victory of the season and his second consecutive in recent weeks at the world center of racing.
Ryan Blaney received a push from Kyle Busch to overtake and beat William Byron in an eight-lap dash to win the FireKeepers Casino 400 at the Irish Hills on Sunday, August 22.
