The victory was the first of Keselowski's Nationwide Series career.
Keselowski was fifth with 29 laps to go, but took the lead from Clint Bowyer with five laps to go.
"This is awesome, you know I came a long way to get here and I owe a lot of people," said Keselowski. "Dale (Earnhardt Jr.) kept me in the car when I had bad weeks and now I had a good week to show him he was right."
Joey Logano, on the pole for the 225-lap race, was knocked out on lap 88 when he got spun by Greg Biffle, who was trying to avoid Kyle Busch who had slid up the track. The accident destroyed Logano's front end, including the radiator, and he spent a lot of the evening in the garage watching his team make repairs.