The Giants finished the 2012 season as World Series Champions. During the postseason Arias appeared in 12 games, all of them as a mid- to late-inning replacement. On October 10, during the Division Series against the Cincinnati Reds, Arias entered the game in the fourth inning and had two hits in three times at bat. Both hits were doubles, after both of which Arias eventually scored runs in a game the Giants won 8–3. Overall for the postseason, Arias went 3-for-8 (.375) with three runs scored.