The 2009 Major League Baseball season began on April 5, 2009; the regular season was extended two days for a one-game playoff between the Detroit Tigers and the Minnesota Twins for the American League Central title. The postseason began the next day with the Division Series. The World Series began on October 28, and ended on November 4, with the New York Yankees defeating the Philadelphia Phillies in six games. This was the second time the season was completed in November. The only other occasion was the 2001 World Series, because of the delaying of the end of that season due to the September 11 attacks as November baseball would be guaranteed when Game 4 was played on Sunday, November 1. Had the 2009 World Series gone the full seven games, Game 7 would've been played on November 5, the latest date ever scheduled for a World Series game. It became the latest date for a World Series game in 2022. The American League champion had home field advantage for the World Series by virtue of winning the All-Star Game on July 14 at Busch Stadium in St. Louis, Missouri, 4–3. In addition, the annual Civil Rights Game became a regular season game, and was played June 20 at Great American Ball Park in Cincinnati, Ohio, when the host Cincinnati Reds lost to the Chicago White Sox in an interleague game, 10–8. Both teams wore replicas of their 1965 uniforms in the contest.

The 2009 World Series was the championship series of Major League Baseball's (MLB) 2009 season. As the 105th edition of the World Series, it was a best-of-seven playoff 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, winning their 27th World Series championship.