The 2009 World Series was the 105th edition of Major League Baseball's (MLB) championship series. The best-of-seven playoff was contested between the Philadelphia Phillies, champions of the National League (NL) and defending World Series champions, and the New York Yankees, champions of the American League (AL). The Yankees defeated the Phillies, 4 games to 2, to win their 27th World Series championship. The series was played between October 28 and November 4, broadcast on Fox, and watched by an average of roughly 19 million viewers. Due to the start of the season being pushed back by the 2009 World Baseball Classic in March, this was the first World Series regularly scheduled to be played into the month of November. This series was a rematch of the 1950 World Series.

Home field advantage for the Series went to the AL for the eighth straight year as a result of its 4–3 win in the All-Star Game. The Phillies earned their berth into the playoffs by winning the National League East. The Yankees won the American League East to earn their berth, posting the best record in the Major Leagues. The Phillies reached the World Series by defeating the Colorado Rockies in the best-of-five National League Division Series, and the Los Angeles Dodgers in the best-of-seven NL Championship Series (NLCS). The Yankees defeated the Minnesota Twins in the American League Division Series and the Los Angeles Angels of Anaheim in the AL Championship Series (ALCS) to advance to their first World Series since 2003. As a result of their loss, the Phillies became the first team since the 2001 Yankees to lose the World Series after winning it the previous year.