Arroyo finished the 2012 season by going 12–10 with a 3.74 ERA. Arroyo was chosen by Reds' manager Dusty Baker to start Game 2 of the 2012 National League Division Series versus the San Francisco Giants. He took a perfect game into the fifth inning, and allowed only two base-runners (a base hit with two outs in the fifth, and a walk in the seventh) in seven scoreless innings. The Reds won the game 9–0 to take a 2–0 series lead. The win was Arroyo's first in thirteen postseason appearances, including five starts.