The 1971 World Series matched the defending champions Baltimore Orioles against the Pittsburgh Pirates, with the Pirates winning in seven games. Game 4, played in Pittsburgh, was the first-ever World Series game scheduled to be played at night.

The two teams proved to be evenly matched, as the Series went the full seven games, with the Pirates' Steve Blass pitching a complete game four-hitter in winning Game 7, 2–1, against Mike Cuellar and the Orioles.

In what would be his final World Series appearance, The Pirates' Roberto Clemente became the first Spanish-speaking ballplayer to earn World Series MVP honors. Clemente hit safely in all seven games of the Series, duplicating a feat he had performed in 1960.

Bruce Kison, who appeared in two games and finished with 6.1 innings pitched, tied the record set during the 1907 World Series when he hit three batters during a single series.

These two teams would meet again in the fall classic eight years later, with the same result.

The Pirates won the National League East by seven games over the St. Louis Cardinals then defeated the San Francisco Giants, three games to one, in the National League Championship Series. The Orioles won the American League East by 12 games over the Detroit Tigers then swept the Oakland A's in the American League Championship Series.

The Orioles were coming off their third straight AL playoff series sweep (twice over the Minnesota Twins, once over the Oakland A's) and their third straight season with over 100 wins (1969 — 109, 1970 — 108, 1971 — 101). Featuring four (4) pitchers with 20 or more wins (Dave McNally — 21, Mike Cuellar — 20, Pat Dobson — 20, Jim Palmer — 20), the booming bats of sluggers Frank Robinson (28, 99, .281) and Boog Powell (22, 92, .256), and the sure hands of Brooks Robinson at third and Mark Belanger at short, the O's were primed to defend their title.

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