Bracket

NOTE: Due to a strike in mid-season, the season was divided into a first half and a second half. The division winner of the first half (denoted E1, W1) played the division winner of the second half (denoted E2, W2).

Other awards

• Outstanding Designated Hitter Award: Greg Luzinski (CWS)
• Roberto Clemente Award (Humanitarian): Steve Garvey (LAD)
• Rolaids Relief Man Award: Rollie Fingers (MIL, American); Bruce Sutter (STL, National).

Player of the Month

Pitcher of the Month

January–March

• January 15 – In his first year of eligibility, former St. Louis Cardinals pitcher Bob Gibson is the only person elected to the Hall of Fame by the Baseball Writers' Association of America. Players falling short of the 301 votes needed for election include Don Drysdale (243), Gil Hodges (241), Harmon Killebrew (239), Hoyt Wilhelm (238) and Juan Marichal (233).
• January 23 – Fred Lynn was traded by the Boston Red Sox with Steve Renko to the California Angels for Frank Tanana, Jim Dorsey, and Joe Rudi.
• February 12 – Reputedly because the Boston Red Sox mailed out his contract two days late, catcher Carlton Fisk is declared a free agent. He will later sign with the Chicago White Sox.
• March 11 – Johnny Mize and Rube Foster are elected to the Hall of Fame by the Special Veterans Committee. Mize hit .312 with 359 home runs in 15 seasons for the Cardinals and New York Giants, while Foster was a star pitcher, manager and pioneer of the Negro leagues during the first quarter of the 20th century.

April–June

• April 9 – After pitcher Jerry Reuss pulls a muscle, rookie Fernando Valenzuela is given his first starting assignment. His first Major League start results in a five-hit shutout. It is the beginning of what will be called "Fernandomania" in Southern California.
• April 10 – Carlton Fisk debuts with the Chicago White Sox, coincidentally in Fenway Park against his former team, the Boston Red Sox. Fisk hits a three-run home run in the eighth to secure a 5–3 win for Chicago.
• April 18 – Tom Seaver of the Cincinnati Reds records his 3000th career strikeout. Keith Hernandez is the victim.
• April 18–19 – Minor league teams from Pawtucket and Rochester clash in a 33 inning game that extends eight hours and 25 minutes; the longest professional baseball game up to that time. Future Hall of Famers Wade Boggs and Cal Ripken Jr. go a combined 6-for-25 in the game.
• April 27 – Just 18 days after his first start, Fernando Valenzuela has grabbed the attention of the baseball world. In just his fifth start, he pitches his fourth complete game shutout running his record to 5–0 with a microscopic 0.20 ERA. He is also batting over .400 to help his own cause.
• April 29 – Steve Carlton of the Philadelphia Phillies records his 3000th career strikeout. April 1981 is the only month in history to have two pitchers reach this milestone. He is the first left-handed pitcher in Major League history to reach that mark.
• May 10 – In the second game of a doubleheader, Charlie Lea of the Montreal Expos no-hits the San Francisco Giants 4–0, the first no-hitter ever pitched at Olympic Stadium.
• May 15 – Len Barker of the Cleveland Indians pitches a perfect game against the Toronto Blue Jays, 3–0, at Cleveland Municipal Stadium. He struck out 11, all swinging, after the third inning and never had a 3-ball count on any batter on a misty, rain-soaked night where only 7,290 fans took in the game. Current Indians broadcaster Rick Manning caught the 27th out of the night on a fly ball to center field. Barker's catcher, Ron Hassey will later catch Dennis Martínez's 1991 perfect game making him the first catcher in history to catch two perfect games.
• May 25 – Carl Yastrzemski plays in his 3,000th major league game, scoring the winning run in Boston's 8–7 triumph over Cleveland. Yaz joins Ty Cobb, Stan Musial and Hank Aaron as the fourth major leaguer to appear in 3,000 games.
• May 28 – After Kansas City Royals player Amos Otis hits a grounder along the third-base line at the Seattle Kingdome, Mariners player Lenny Randle gets down onto his hands and knees and blows on the ball, in an attempt to make it a foul ball.^[29]
• June 5 – Nolan Ryan issues the 1,777th walk in his career, breaking the record previously held by Early Wynn.
• June 10 – Pete Rose hits a Nolan Ryan pitch for the 3,630th safe hit of his career; tying Stan Musial's National League record for career hits.
• June 12 – After meeting with major league owners for most of the previous day, players' union chief Marvin Miller announces, "We have accomplished nothing. The strike is on", thus beginning the longest labor action to date in baseball history. By the time the season resumes on August 10, 706 games (38 percent of the season schedule) will have been canceled.
• June 16 – In the midst of the players' strike, William Wrigley III announces the sale of the Chicago Cubs to the Tribune Company for $20 million. This ends the decades long association between the Wrigley family and the Cubs.

July–September

• August 6 – As a result of the nearly two-month interruption in play because of the strike, major league owners elect to split the 1981 season into two halves, with the first-place teams from each half in each division (or a division's runner-up team in the second half, if the same club were to win both halves (The Sporting News Official Baseball Guide for 1982, p. 13) meeting in a best-of-five divisional playoff series. The last time the major leagues had played a split season was 1892. The Oakland Athletics, New York Yankees, Philadelphia Phillies and Los Angeles Dodgers suddenly find themselves guaranteed playoff spots as first-half champions (a problem noted at this time is that those teams will not have much left to play for in that year's regular season).
• August 9 – At Cleveland Stadium, the National League wins its tenth consecutive All-Star Game over the American League, 5–4. Gary Carter hits two home runs and is selected the MVP. The 1981 Midsummer Classic becomes the first and, as of 2020, the only All-Star Game ever played on a Sunday, and the second ever played during the month of August, the first having taken place on August 3, 1959.
• September 4 – In the conclusion of the longest game in Fenway Park history, the Seattle Mariners beat the Boston Red Sox 8–7 in 20 innings. The game began on September 3, but was suspended after 19 innings with the score tied 7–7.
• September 6 – Despite having won the first-half American League East title, New York Yankees manager Gene Michael is replaced by Bob Lemon, who managed the club in 1978–79. The Yankees are under .500 in the second half of the season.
• September 6 – The Los Angeles Dodgers' Fernando Valenzuela beats the St. Louis Cardinals 5–0 to tie the National League record of seven shutouts by a rookie pitcher.
• September 26 – Nolan Ryan of the Houston Astros breaks the record of four no hitters by pitcher Sandy Koufax by pitching his fifth career no hitter in the Astrodome against, coincidentally, Koufax's former team, the Los Angeles Dodgers.
• September 30 – The Kansas City Royals defeat the Minnesota Twins, 5–2, to clinch the second half of the American League Western Division title. More importantly, it is the last Major League game to be played at Metropolitan Stadium, as the Twins prepare to move into the new Hubert H. Humphrey Metrodome.

October–December

• October 3 – Bob Horner hits two home runs and scores the winning run to give the Atlanta Braves a 4–3 win over the Cincinnati Reds, and the Houston Astros the second-half title in the NL West division. Cincinnati, which lost the first-half title to the Dodgers by half a game, will finish with the best overall record (66–42) in the major leagues, but will miss the playoffs as a result of not having won either half's division title.
• October 3 – The Milwaukee Brewers (playing since 1970) and Montreal Expos (since 1969) clinch their first postseason appearances. Milwaukee beats Detroit 2–1 to wrap up the second-half title in the AL East division, while Montréal edges the Mets 5–4 to win the NL East's second playoff spot. (St. Louis finishes with the best overall record in the NL East but misses the playoffs for the same reason as the Cincinnati Reds.)
• October 5 – The Kansas City Royals shut out Cleveland 9–0 in the first game of a scheduled doubleheader to clinch the second-half title in the AL West. The second game is canceled as irrelevant. This was a make-up game after the scheduled season ended the day before.
• October 19 – Rick Monday of the Los Angeles Dodgers hits a ninth-inning home run to break a 1–1 tie and secure a Game 5 victory in the National League Championship Series. The losing Montréal Expos had been leading the series two games to one in what would be their only postseason appearance.
• October 28 – Pedro Guerrero drives in five runs, and pitcher Burt Hooton and the Los Angeles Dodgers beat the New York Yankees 9–2 to win the 1981 World Series in six games. In a remarkable postseason, the Dodgers rallied from game deficits of 2–0 against the Astros in the division series, 2-1 against the Expos in the National League Championship series, and 2–0 against the Yankees in the World Series. Guerrero, Ron Cey and Steve Yeager are named co-MVPs.
• November 11 – Fernando Valenzuela of the Los Angeles Dodgers wins the National League Cy Young Award, becoming the first rookie to win the award.
• November 25 – Rollie Fingers of the Milwaukee Brewers becomes the first relief pitcher ever to win the American League MVP Award, edging Rickey Henderson of the Oakland Athletics, 319 to 308. Fingers saved 28 games while posting a 1.04 ERA.
• December 2 – Following the strike-shortened season, Los Angeles Dodgers pitcher Fernando Valenzuela becomes the third consecutive Dodgers player to be named National League Rookie of the Year. The Mexican lefthander posted a 13–7 record with a 2.48 ERA and led the NL in strikeouts (180), games started (25), complete games (11), shutouts (eight) and innings pitched (1921⁄3). His 13 wins tied him with Steve Carlton in second place behind Tom Seaver, who finished with 14. Valenzuela also made his first All-Star appearance and received both the Cy Young and TSN Rookie of the Year awards.