This was the final season the majority of MLB teams wore wool flannel uniforms. The Pirates and Cardinals wore double knit uniforms of nylon and rayon throughout 1971, and the Orioles gradually phased out flannels, going all-double knit in time for the ALCS. By 1973, flannel uniforms completely disappeared from the MLB scene.
Three of the four division races were anticlimactic; the only race was in the N.L. West between old rivals Los Angeles Dodgers and San Francisco Giants. The Giants led by 8.5 games on September 1 but the Dodgers chipped away. In mid September, the Dodgers won 8 in a row, including 5 over the Giants to narrow the gap to one game. But they could get no closer; ultimately both teams won on the final day of the season and the Giants won the division by 1 game.
February 9 – Former Negro Leagues pitcher Satchel Paige is nominated for the Hall of Fame. On June 10, the Hall's new Veterans Committee will formally select Paige for induction.
March 7 - The Milwaukee Brewers and Oakland Athletics play a spring training game where only three balls are needed for a walk. The Athletics won 13-9, with the game featuring 19 walks. The experiment is not tried again.
April 6 – Bill White, a former NL first baseman, became the first African-American to do play-by-play as part of a regular broadcast crew of a team, when the New York Yankees opened the season with a game in Boston.
July 7 – Commissioner Kuhn announces that players from the Negro Leagues elected to the Hall of Fame will be given full membership in the museum. It had been previously announced that they would be honored in a separate wing.
August 28 – Phillies pitcher Rick Wise hits two home runs, including a grand slam off Don McMahon, in the second game of a doubleheader, duplicating his feat in his June no-hitter. Wise beats the Giants 7–3.
September 30 – The Washington Senators' lead 7–5 in their last home game, but forfeit the game to the New York Yankees, when, with two outs in the top of the ninth, fans storm the field. The Senators moved to Dallas, Texas, and became the Texas Rangers for the 1972 season, leaving the Nation's Capital without an MLB team until 2005.
November 2 – The Orioles' Pat Dobson pitches a no-hitter against the Yomiuri Giants, winning 2–0. It is the first no-hitter in Japanese-American baseball exhibition history. The Orioles compile a record of 12–2–4 on the tour.