As one of the American League's eight charter teams in 1901, the franchise spent its first year as a major league club in Milwaukee, Wisconsin, as the Milwaukee Brewers before moving to St. Louis, Missouri, to become the St. Louis Browns in 1902. After 52 years in St. Louis, the franchise was purchased in November 1953 by a syndicate of Baltimore business and civic interests and adopted its current name in honor of the official state bird of Maryland.

Baltimore outfielder Brady Anderson went into the final game of the 1996 season with 49 home runs. In his first at-bat, he hit his 50th homer off Cy Young Award winner Pat Hentgen, breaking Frank Robinson's record for most home runs in a season by a Baltimore Oriole. Anderson's record would be broken in 2013 by Christ Davis, who hit 53.

In 1951, Bill Veeck, the colorful former owner of the Cleveland Indians, purchased the Browns and extended the promotions and wild antics that had made him famous. His most notorious stunt in St. Louis came on August 19, 1951, when he had Eddie Gaedel, a 3-foot 7 inch, 65-pound little person, bat as a pinch hitter. When Gaedel stepped to the plate he was wearing a Browns uniform with the number 1/8 and little slippers turned up at the end like elf's shoes. With no strike zone to speak of, Gaedel walked on four straight pitches. The stunt infuriated American League President Will Harridge, who voided Gaedel's contract the next day.

Brooks Robinson won the World Series MVP Award hitting .429, broke the record for total bases in a five-game series with 17, tied the record for most hits in one game with four, and tied teammate Paul Blair for most hits in a five-game Series with nine. Total Baseball described Robinson's fielding as "other-worldly defense at third (which) gave Reds right-handed hitters nightmares through the Series." Upon hearing that Robinson won the MVP award and a new car from Toyota, Reds' catcher Johnny Bench said, "If we had known he wanted a car that badly, we'd all have chipped in and bought him one."

In Game 3 of the 1970 World Series, Baltimore left-hander Dave McNally had a banner day, pitching a complete game and scattering nine hits, while also connecting for a grand slam in the sixth inning off reliever Wayne Granger to break the game open.

In 1922, George Sisler hit safely in 41 consecutive games, an American League record that stood until Joe DiMaggio broke it in 1941. His .420 batting average is the third-highest of the 20th century, surpassed only by Nap Lajoie's .426 in 1901 and Rogers Hornsby's .424 in 1924.

During his 17-year tenure as manager of the Baltimore Orioles, Earl Weaver was ejected from a major-league record 91 games. He was twice ejected from games before they even started, and on three separate occasions, he was ejected from both games of a double header!

Cal Ripken Jr., nicknamed "The Iron Man", holds the MLB record for consecutive games played with 2,632, surpassing Lou Gehrig's streak of 2,130 that had stood for 56 years and that many deemed unbreakable. In 2007, the 19-time All-Star and two-time American League MVP was elected to the National Baseball Hall of Fame in his first year of eligibility with 98.53% of votes, the sixth-highest election percentage ever.

On May 8, 2018, Dylan Bundy set an unfortunate record against the Kansas City Royals by allowing four home runs without recording a single out. In total, Bundy gave up 5 hits, 7 runs, and 2 walks before being pulled in the first inning.

The 1971 Orioles are one of only two Major League Baseball clubs (the 1920 Chicago White Sox being the other) to have four 20-game winners in a season: Mike Cuellar (20), Pat Dobson (20), Jim Palmer (20), and Dave McNally (21).