After 10 cautions and 14 changes of the lead, Chastain ensured his #1 Chevrolet was the car to take the checkered flag after 267 laps of action, finishing ahead of the likes of William Byron and Michael Truex Jr, the latter of whom he passed after a late restart.
It was a thrilling race that has dramatically changed the playoff picture, with just six races left in the series.
Chastain claims victory in Kansas
Chastain's win was his first of the season, and his first since the last race of the 2023 season.
The 31-year-old has suffered mixed results in 2024, with just five top-five finishes before Sunday's win.
Chastain's return to winning ways delighted fans in Kansas, and the American got to show off his unusual trademark celebration, too.
Chastain stood on the roof of his #1 Chevrolet and slammed a watermelon on the ground, seeing it explode all over the asphalt.
The American racer also showcased his skills by spinning his car around, performing donuts, much to the fans' delight.