Busch, in the No. 18 Joe Gibbs Racing Toyota, bumped Kyle Larson's No. 42 Ganassi Racing Chevrolet between turns 3 and 4 with five laps to go and raced to his seventh NASCAR Monster Energy Cup Series win at Bristol and his track-record 21st win overall.
It marked the fifth time in his Cup Series career that Busch has scored back-to-back wins, following his win at Texas a week earlier. It was his 45th career victory, putting him past Hall of Famer Bill Elliott for 16th place on NASCAR's all-time win list. But the key for his winning move was not giving Larson a chance to get even.
"It was all about chasing down that No. 42 and being able to get to him," Busch said. "I thought about holding that bump-and-run deal to the last lap, but I took my chances with it. If he got back to my rear bumper, so be it, that's fair game to race that way. Fortunately, I was able to get away and he wasn't able to get to me."
Larson was understandably frustrated after having the dominant car most of the day. He had raced out to a seven-second lead on Sunday before the race was stopped for rain. He had a commanding lead again on Monday, until a late caution for Brad Keselowski's Ford blowing a left front tire and spewing debris on the track led to a late-race showdown.
It was the fourth time which Larson has finished runner-up to Busch at BMS. The first three times came in NASCAR Xfinity Series races.
"As soon as I restarted, I was extremely loose and just didn't have any grip," said Larson, who led four times for a race-high 200 laps. "I thought I could get going, but I never really did. I hate that I didn't win. It's another one at Bristol that got away. Some race. I've been beaten by Kyle about every time I've raced here, too. That gets frustrating after a while."
It was the opposite feeling for third-place finisher Jimmie Johnson. The seven-time NASCAR champion saw his career-long winless streak reach 31 races, but his first top-five finish of the season and the first since Dover last October.
"We've been talking about our cars performing better and driving better, but to finally back it up with a solid finish is exactly what we needed," said Johnson, driver of the No. 48 Hendrick Motorsports Chevrolet. "I really feel like we're rolling in the right direction now."
Ricky Stenhouse Jr. in a Ford and Alex Bowman in a Chevrolet rounded out the top five.
Ford drivers Aric Almirola, Kevin Harvick, Clint Bowyer and Joey Logano took the next four positions, followed by Ryan Newman in 10th.
Keselowski won both Stage 1 and Stage 2 of the Food City 500.
The driver of the No. 2 Team Penske Ford used pit strategy to get out front in Stage 1, but it put him back in the 14th place was halted for weather after 204 laps Sunday.
With new left-side tires, Keselowski quickly stormed through the field when the race resumed. He passed leader Larson for the lead on lap 244 and then held off Busch to win the second stage.