The 1971 Pittsburgh Pirates season was the 90th season for the Pittsburgh Pirates franchise; their 85th in the National League. It involved the Pirates finishing first in the National League East with a record of 97 wins and 65 losses. They defeated the San Francisco Giants three games to one in the NLCS and beat the Baltimore Orioles four games to three in the World Series. The Pirates were managed by Danny Murtaugh, and played their first full season at Three Rivers Stadium, which had opened in July the year before.

The 1971 San Francisco Giants season was the Giants' 89th year in Major League Baseball, their 14th year in San Francisco since their move from New York following the 1957 season, and their 12th at Candlestick Park. The team finished in first place in the National League West with a 90–72 record. The Giants faced the Pittsburgh Pirates in the NLCS, losing three games to one.