Helton made what was arguably the most pivotal play of the Rockies' 2007 season in the second game of a doubleheader against the Los Angeles Dodgers on September 18, 2007. In the bottom of the ninth inning, with two outs and two strikes, Helton hit an emotional two-run walk-off home run off Dodgers closer Takashi Saito. The home run kept the Rockies alive in the bid to win the wild card or National League West title. The Rockies eventually clinched the National League wild card, in a 9–8 extra innings victory over the San Diego Padres in a wild card tiebreaker game, allowing Helton to appear in the playoffs for the first time in his career. Colorado went on to sweep the Philadelphia Phillies in three games of the National League Division Series. Helton hit a triple in the first pitch of his first career playoff at-bat in the opening game against the Phillies at Philadelphia. The Rockies also swept the Arizona Diamondbacks in four games of the National League Championship Series, sending the Rockies on their first trip to the World Series in franchise history. The Rockies went on to lose the World Series to the Boston Red Sox in a four-game sweep.