Familia recorded two saves in the 2015 National League Division Series against the Los Angeles Dodgers, retiring all 16 batters he faced. In the 2015 National League Championship Series against the Cubs, Familia recorded three saves over innings pitched, giving up 2 hits and 2 walks and no runs. Familia struck out Dexter Fowler to send the Mets to the World Series. In game 1 of the 2015 World Series against the Kansas City Royals, he gave up a game-tying home run to Alex Gordon in the ninth inning; the Mets would eventually lose, 5–4, in 14 innings. He gave up the home run to Gordon on a quick pitch, which Familia used to throw off hitters' timing throughout the 2015 season. Familia blew saves in games 4 and 5 as well, both of which the Mets lost, the latter of which ended the series. Familia's three blown saves in the series established a new World Series record. He tied Robb Nen for most save opportunities in one postseason, with eight.