In the 2012 postseason, Affeldt appeared in 10 games, pitching innings, allowing 5 hits and 3 walks against 10 strikeouts and no runs. In Game 4 of the 2012 World Series, Affeldt provided key relief, striking out Detroit Tigers power hitters Miguel Cabrera, Prince Fielder, and Delmon Young in the eighth inning to preserve a 3–3 tie. The Giants would go on to win the game in the tenth inning, completing a sweep of the Tigers, earning Affeldt his second World Series ring. On November 13, 2012, Affeldt signed a three-year, $18 million contract to remain with the Giants through the 2015 season.