After the 2011 season, the Giants re-signed López to a two-year, $8.5 million contract. On July 6, 2012, López gave up his first home run since joining the Giants in 2010 when he allowed a 457-foot home run to Pedro Álvarez in a 6–5 victory over the Pirates. That brought his ERA to 4.00, but he posted a 1.00 ERA over his last 32 games. Following struggles by Santiago Casilla (who had replaced an injured Wilson as the Giants' closer), Giants' manager Bruce Bochy announced on August 7 that the Giants would be going to a "bullpen by committee" strategy, with López, Sergio Romo, and Jeremy Affeldt pitching the final two innings of close games, depending on which hitters they would be facing. Romo and López received most of the save opportunities; Affeldt only had one save after that point. López received six save opportunities after August 7 and converted each of them. In 70 games, López had a 3–0 record, a 2.50 ERA, and 28 strikeouts in 36 innings while converting seven out of nine save opportunities. He stranded 87.9% of inherited runners, the third-best mark in the NL. López made five appearances in the NLDS and the NLCS, allowing no runs as the Giants won both of those series. He did not pitch in the World Series but won his third career World Series ring as the Giants swept the Detroit Tigers.