Busch passed Martin Truex Jr. after the last restart with 21 laps left, then held off Joey Logano down the stretch to collect his fourth win of the season and land a spot in the 12-driver, season-ending playoffs.
Logano made it close at the end despite having to make an out-of-sequence pit stop early in the race due to a vibration.
A bid by defending Sprint Cup Brad Keselowski to make the Chase field suffered a setback when he blew a cylinder while holding a late lead, ending with a 35th-place finish.
Exploding whale video goes viral on Internet
Wisconsin business offering 'therapeutic cuddling' forced to close