Busch, who moved from Joe Gibbs Racing to Richard Childress Racing over the winter, grabbed the lead on lap 143 and held on through a final round of green-flag pitstops to keep clear of Chase Elliott to win by 2.998 seconds.
The win gives the 37-year-old the outright record for most consecutive seasons with at least one victory, as he pulls clear of seven-time NASCAR champion Richard Petty to move on to 19 straight seasons.
Busch is also the final winner on the two-mile track layout at Fontana as it is scheduled to be transformed into a short track and will not be on the 2024 Cup schedule.
In addition, the last time Busch won a Cup race in a car not from Joe Gibbs Racing was 25 March 2007, nearly 16 years ago, when Busch drove for Hendrick Motorsports.
But it wasn’t all smooth sailing for the two-time Cup champion, as he had to overcome a pit speeding penalty and battle his way back to the front of the field.
“Could have, should have, would have last week. I think it’s just phenomenal,” Busch said, reflecting on missing out at the Daytona 500 last weekend. “I can’t thank Richard and Judy [Childress] enough, Austin [Dillon] for calling me and getting me talking and getting me the opportunity to come over here to RCR.
Race winner Kyle Busch, Richard Childress Racing, Chevrolet Camaro
Photo by: Matthew T. Thacker / NKP / Motorsport Images
“The guys did a great job. Everybody that worked so hard in the off-season. We did a lot of sim stuff, a lot of testing in general just trying to get up to speed. There is nothing more rewarding than being able to go to victory lane.”
Ross Chastain led the most laps with 91 but ended up third as he faded towards the end, while his Trackhouse Racing team-mate Daniel Suarez was fourth and Kevin Harvick rounded out the top-five.
With Denny Hamlin sixth, Brad Keselowski bounced back from a crash at the Daytona 500 to take seventh, ahead of Alex Bowman and Austin Dillon, as last weekend’s runner-up at Daytona Joey Logano completed the top 10.
NASCAR Cup – Fontana race results – 200 laps