The 1971 World Series was the championship round of Major League Baseball's (MLB) 1971 season and featured the first night game in its history. The 68th edition of the Fall Classic was a best-of-seven playoff between the defending World Series and American League (AL) champion Baltimore Orioles and the National League (NL) champion Pittsburgh Pirates. The Pirates won the World Series in seven games, in large part because of superstar right fielder Roberto Clemente, whose all-around brilliance was on full display on a national stage. Game 4 in Pittsburgh was the first World Series game played at night.

The World Series is the annual final championship series of Major League Baseball (MLB) in the United States and Canada. It has traditionally been held in October, though some more recent editions were contested in November due to expanded playoffs and/or season delays. It has been contested since 1903 between the champion teams of the American League (AL) and the National League (NL). The winner of the World Series championship is determined through a best-of-seven playoff, and the winning team is awarded the Commissioner's Trophy.