Busch dominated much of the race – leading 121 of the 243 laps – but had to wait a near two-hour weather delay for lightning with the race just five laps old.
Busch powered past Kyle Larson and Denny Hamlin on a restart on lap 184 to move into the lead for the final time but then had to fend off repeated challenges on restarts.
A late-race caution for a wreck involving Austin Dillon and Ricky Stenhouse Jr. – as well as a five-minute red flag for some wall repairs – set up a restart with 15 laps remaining but Busch was once again able to hang on to the lead.
Busch appeared to have a clear path to victory, but Bubba Wallace blew a brake rotor and slammed the wall with five laps to go which set up the two-lap overtime.
But Busch once again held his lead in overtime, to beat Hamlin by 0.517 seconds to earn his third NASCAR win of the 2023 season.
The win is the 63rd of his career and he now has 11 seasons with at least three or more victories.
“That was pretty awesome,” said Busch, who was met by his son, Brexton, on the track after the win. “Man, to sit on the pole, lead a lot of laps, my guys did just a great job today. It was pretty flawless for us. All the fans go out and celebrate with us. We’re going to have a great time with this one. This one is pretty cool.”
Last year’s Gateway winner, Joey Logano, finished third, Larson was fourth ahead of Martin Truex Jr. ended up fifth.
Ryan Blaney, current NASCAR Cup points leader, took sixth place ahead of Daniel Suarez, as William Byron, Michael McDowell – who overcame an early-race spin – and Kevin Harvick completed the top 10.
NASCAR Cup – Gateway race results (243 laps)