The following are the baseball events of the year 1889 throughout the world.
Major league baseball final standings
National League final standings
American Association final standings
National League statistical leaders
American Association statistical leaders
- March 7 – Pittsburgh Allegheny players, Bill Kuehne and Ed Morris, are arrested and charged with operating a gambling house out of their billiard parlor. The charges against both are dropped when the prosecution's star witness fails to appear in court to testify against them.
- March 20 – A New York City sporting goods house receives an order from Japan for baseball equipment. The corresponding letter states that a league will soon be formed as the game has been played there for several months already.
- April 17 – The American Association season begins.
- April 23 – New York Governor David Hill vetoes a bill from the state legislature that would block the street construction at the Polo Grounds.
- April 29 – The New York Giants play their first home game at the St. George Cricket Grounds on Staten Island. The right-fielder plays on a stage used for theatre productions in the multi-purpose complex.
- May 1 – George Keefe of the Washington Nationals sets a record by walking seven batters in one inning in a game against the New York Giants.
- May 2 – Yank Robinson of the St. Louis Browns is fined and suspended after getting into a shouting match with Browns owner Chris von der Ahe. His teammates nearly refuse to make a trip to Kansas City and do lose three straight games to the Cowboys amid suspicion they are throwing the games because of Robinson's suspension.
- May 6 – Chris von der Ahe, owner of the Browns, rescinds Yank Robinson's suspension. The Browns respond by beating the Kansas City Cowboys, their first victory since the suspension.
- May 7 – Yank Robinson returns to the Browns lineup and goes 4–6 at the plate, leading St. Louis to a 21–0 win over the Columbus Solons.
- May 9 – Amos Rusie makes his major league debut with the Indianapolis Hoosiers.
- May 14 – The Pittsburgh Alleghenys suspend pitchers Ed Morris and Pete Conway, so they will not have to pay the salaries for the two sore-armed pitchers. Morris will return in three weeks although he will never again be an effective pitcher while Conway, a 30 game in 1888, will never pitch again.
- May 19 – Most of the seating is destroyed by fire at Brooklyn's Washington Park. The stands will be rebuilt within a month.
- May 24 – Bill Kuehne of the Pittsburgh Alleghenys sets a record by handling 13 chances at third base in one game.
- May 25 – When Dave Orr of the Columbus Solons refuses to leave the field after being ejected, umpire Fred Goldsmith declares the game forfeited to the visiting Brooklyn Bridegrooms. Both teams refuse to abide by the forfeit and complete the game after Orr is replaced by a substitute.
- May 30 – The Brooklyn Bridegrooms defeat the St. Louis Browns 9–7 in front of the largest crowd in American Association history. 22,122 fans fill Washington Park, which has only 3,000 seats available after the fire 11 days earlier that destroyed the stands.
- June 7 – Pete Browning hits for the cycle in a losing cause, as the Louisville Colonels fall to the Philadelphia Athletics, 9–7. It is Louisville's 14th consecutive loss and the second time Browning has hit for the cycle in his career.
- June 11 – Dan Brouthers strikes out in a game for the first time this season. Brouthers will end the year with only six strikeouts in over 550 plate appearances.
- June 13 – After the Louisville Colonels lose their 19th straight game, owner-manager Mordecai Davidson threatens to fine each player $25 if they lose their next game, even though the players are already owed back pay by Davidson.
- June 15 – Protesting Mordecai Davidson's threat of fines, only six Louisville Colonels players show up for their game against the Baltimore Orioles. Davidson is forced to pick up three Baltimore amateurs to play the outfield. Charles Fisher, John Traffley and Mike Gaule each make the only appearance of their careers as Louisville loses their 20th in a row.
- June 17 – After consulting Baltimore manager, Billy Barnie, the striking players of the Louisville Colonels return to the field for a doubleheader. The Colonels blow a ninth inning 6–3 lead in Game 1 to lose and manage only one hit while committing seven errors to drop the second game.
- June 19 – Center fielder Dummy Hoy sets a major league record by throwing three runners out at the plate in one game.
- June 22 – The Sporting News reports that major league players are unhappy with the classification system for pay and no say or share in their sale to other clubs, and that a strike is imminent beginning in early July.
- June 22 – The Louisville Colonels drop a pair of games to the St. Louis Browns to extend their losing streak to 26 games, which still stands as the major league record.
- June 23 – Louisville finally gets a win in defeating the Browns 7–3.
- June 24 – Louisville owner-manager Mordecai Davidson resigns as manager and hires an Eclipse Park employee as the new manager, although right fielder Jimmy Wolf will actually run the team.
- June 28 – Billy Hamilton hits three triples in the first game of a doubleheader and then adds another one in the night cap to set a record for most triples in a doubleheader.
- Early July – John Montgomery Ward convinces representatives for The Brotherhood of Professional Base-Ball Players hold off on their planned strike for a couple of weeks until he can present them with a better long-term solution.
- July 2 – Louisville Colonels owner Mordecai Davidson, unable to pay the players salaries, turns the team over to the American Association. The AA will announce new ownership for the team within 3 days.
- July 6 – Player-manager John Morrill, with his team in last place in the National League at 13–40 and a personal batting average of .185, is let go by the Washington Nationals after leaving the team to go see ailing relatives in Worcester.
- July 8 – The New York Giants play their first game at the newly relocated Polo Grounds. The stadium will remain a fixture in major league baseball until its demolition in 1964.
- July 12 – John Clarkson of the Boston Beaneaters is taken out after pitching five innings of no-hit ball in order to rest him for his next start. His teammate, reliever Bill Sowders, allows one hit over the last four innings for the combined one-hitter.
- July 14 – Albert Spalding publishes his ideas for the classification and structure of the minor leagues. His ideas will be the foundation of minor league baseball that last to the present day.
- July 14 – At a secret meeting of the Brotherhood of Professional Base-Ball Players held at the Fifth Avenue Hotel in New York City, John Montgomery Ward instructs Brotherhood representatives that "each player look up the feasibility of securing capital in his own city" for the purpose of starting a competing league that would give the players an equal say in all baseball matters.
- July 24 – Joe Dowie will collect only 17 hits in his one season of major league baseball, but five of them come on this day in as he helps the Baltimore Orioles to an easy 17–3 win over the Louisville Colonels.
- July 26 – Jay Faatz hits possibly the shortest grand slam ever when he hits a ball that ricochets off of the third baseman's foot and rolls under some temporary bleachers placed close to third base. Faatz circles the bases as the ball is still in play according to the park's ground rules.
- July 29 – Mike ″King″ Kelly of the Boston Beaneaters robs the Philadelphia Quakers of a victory when, after Sam Thompson had apparently hit a long drive over the right field fence for a home run, he manages to throw a ball back into the infield that holds Thompson on the bases. While the Quakers argue that Kelly used a different ball, the umpire rules it is the game ball and allows the play to stand. Thompson is stranded on base as the Beaneaters go on to win 7–6 in extra innings.
- August 7 – The Cleveland Spiders score 14 runs in the third inning, still a record for that inning, during a 20–6 win over the Washington Nationals.
- August 8 – Shortstop Jack Glasscock of the Indianapolis Hoosiers hits for the cycle against the New York Giants. Indianapolis wins, 14–4.
- August 12 – The first-place St. Louis Browns complete a three-game sweep in St. Louis over the second place Brooklyn Bridegrooms, with an 11–0 win in front of 32,911 fans.
- August 15 – Cleveland Spiders outfielder Larry Twitchell hits for the cycle in a 19–8 victory over the Boston Beaneaters. In addition, the Spiders become the first Major League team to score a run in every inning of a game.
- August 18 – The Cincinnati police stop a scheduled Cincinnati Red Stockings Sunday game after a court ruling prohibits Sunday baseball. The ban will be a factor in the Red Stockings' decision to jump to the National League in 1890.
- August 25 – The Red Stockings are again stopped by police from playing a Sunday game.
- September 1 – After having led the American Association all but three days of the season, the St. Louis Browns fall out of first place by losing in extra innings to the Columbus Solons.
- September 3 – Con Daily of the Indianapolis Hoosiers makes the final out in a 7–6 loss to the Boston Beaneaters just after the umpire had apparently called time. Given a second chance, Daily hits a two-run single to give the Hoosiers an 8–7 win.
- September 7 – In a critical two-game series, the St. Louis Browns leave the field in Brooklyn in the ninth inning leading 4–2 claiming it is too dark to continue play. Umpire Fred Goldsmith disagrees and forfeits the game to the Brooklyn Bridegrooms. Several Browns players are hit by thrown bottle as they leave the park.
- September 8 – Citing safety concerns, the Browns fail to show for their game against Brooklyn and forfeit for the second day in a row, giving the Bridegrooms a 4½ game lead over the Browns.
- September 11 – In a season that will have 135 rainouts between the two leagues, every scheduled game in both leagues is postponed due to rain on this day.
- September 23 – The American Association, in an emergency meeting, overturns the forfeit by the St. Louis Browns on September 7 and awards them a 4–2 victory. The ruling draws the Browns back to within 4½ games of the Brooklyn Bridegrooms.
- September 25 – The Brotherhood of Professional Base-Ball Players' organizational plan for a new Players' League is leaked to the press in New York City. It calls for clubs to be owned jointly by players and capitalists.
- September 27 – Out of the pennant race, the Philadelphia Quakers make a largely symbolic move by releasing Brotherhood activists outfielder George Wood, who is batting .251, and pitcher Dan Casey, who has a 6–10 record.
- October 5 – The New York Giants clinch the National League pennant on the last day of the season with a 5–3 win coupled with the Boston Beaneaters 6–1 loss. It was the first time in major league history that the pennant was determined on the last day of the season.
- October 6 – The Brooklyn Bridegrooms complete their home schedule with a 9–0 victory. Brooklyn sets a new National League season attendance record by drawing 353,690 fans in a season.
- October 15 – Having to win their final five games to win the American Association pennant, the St. Louis Browns lose in their first try, giving the flag to the Brooklyn Bridegrooms who have already completed their season.
- October 18 – The Brooklyn Bridegrooms take Game 1 of the best-of-11 World Series with a 12–10 victory over the New York Giants.
- October 19 – The Giants even the series by taking Game 2 by a score of 6–2.
- October 22 – The Bridegrooms take Game 3 by a score of 8–7 in a game called because of darkness that ends with the Giants having the bases loaded and one out in the top of the ninth inning.
- October 23 – In another game called early by darkness, New York scores five runs in the top of the sixth inning to tie the game at seven, only to see the Bridegrooms win it on a three-run homer by Oyster Burns in the bottom of the sixth.
- October 24 – The Giants win Game 5 by a score of 11–3.
- October 25 – New York evens the series at three games apiece by tying the game at 1 with a run in the ninth inning. The Giants then win it in the 11th inning as Hank O'Day outlasts Adonis Terry in the 2–1 extra inning thriller.
- October 26 – New York wins again, taking an 11–7 triumph over the Bridegrooms.
- October 28 – The Giants win their fourth straight game by defeating Brooklyn 16–7.
- October 29 – The New York Giants win their second consecutive World Series title by beating the Brooklyn Bridegrooms, 3–2, for their fifth straight win in taking the series 6 games to 3.
^Someş sources show 1890
- January 15 – Lew Brown, 30, catcher for 1877 NL champion Boston Red Caps and who batted .305 for the 1878 Providence Grays.
- January 26 – Tom Gillen, 26, catcher for the 1884 Philadelphia Keystones of the Union Association.
- February 24 – Jim McElroy, 26, pitched for 2 teams in 1884.
- March 28 – Tom Smith, 37?, played in 3 games for the 1875 Brooklyn Atlantics.
- April 12 – Frank Ringo, 28, journeyman utility player from 1883–1886.
- May 20 – Oscar Walker, 35, center fielder and first baseman who led the American Association in home runs with the 1882 St. Louis Browns.
- June 9 – Mike Burke, 35?, reserve for the 1879 Cincinnati Reds.
- June 20 – Pat McGee, age unknown, utility player from 1874–1875.
- July 22 – John Greason, 37, back-up pitcher for the 1873 Washington Blue Legs.
- August 8 – Harry McCormick, 33, pitcher who won 41 games from 1879–1883.
- September 9 – Jack Gorman, 30?, journeyman utility player in 1883–1884.
- Nemec, David (1994). The Beer and Whiskey League: The Illustrated History of the American Association-Baseball's Renegade Major League. New York: Lyons & Burford, Publishers ISBN 1-55821-285-X