The 2018 TicketGuardian 500 was a Monster Energy NASCAR Cup Series race held on March 11, 2018, at ISM Raceway in Avondale, Arizona. Contested over 312 laps on the one-mile (1.6 km) oval, it was the fourth race of the 2018 Monster Energy NASCAR Cup Series season. It would also be the last Phoenix race to be using the 2011 reconfiguration as the start/finish line will be moved to the back-straightaway just past turn two for the November race.

The 2018 Monster Energy NASCAR Cup Series was the 70th season of NASCAR professional stock car racing in the United States, and the 47th modern-era Cup series season. The season began at Daytona International Speedway with the Advance Auto Parts Clash, the Can-Am Duel qualifying races and the 60th running of the Daytona 500. The regular season ended with the Brickyard 400 on September 9, 2018. The playoffs ended with the Ford EcoBoost 400 at Homestead-Miami Speedway on November 18, 2018. Martin Truex Jr. was the defending champion, having won his first in the series.