The 1934 World Series was the championship series in Major League Baseball for the 1934 season. The 31st edition of the World Series, it matched the St. Louis Cardinals against the Detroit Tigers. The Cardinals' "Gashouse Gang" won in seven games for their third championship in eight years.

The Cardinals and Tigers split the first two games in Detroit, and Detroit took two of the next three in St. Louis. But St. Louis won the next two in Detroit, including an 11–0 embarrassment in Game 7 to win the Series. The stars for the Cardinals were Joe ("Ducky") Medwick, who hit .379 and one of St. Louis' two home runs, Jack Rothrock, who hit a series-high 6 RBI’s, and the meteoric ("Me 'n' Paul") Dean brothers, Dizzy and Paul (or "Daffy") Dean, who won two games each with a combined 28 strikeouts and a minuscule 1.43 earned run average. The 1934 World Series was also the last in which both teams were led by player-managers, in this case the Cardinals' Frankie Frisch and the Tigers' Mickey Cochrane.

The two teams have met twice in the World Series since 1934; in 1968 (Tigers won in seven) and 2006 (Cardinals won in five). Tiger pitcher Denny McLain, winner of Game 6 in 1968 (coasting home on the Tigers' record-tying ten-run second inning rally on the road), had gone 31–6 during the season, upstaging "Diz" with his mere 30–7 that year, who at 57 went onto the Tiger Stadium field in a big cowboy hat to be photographed with McLain moments after the walk-off hit that had given the latter his thirtieth win of the season. As of 2021, they are the last two 30-game winners in the major leagues.

The Cardinals, led by the Dean brothers, used only six other pitchers in amassing a team earned-run average of 2.34 for their 1934 Series victory,

Pete Fox played for the losing team, yet became the only player in Series history, as of 2021^[update], to hit six doubles in a World Series.

For his top-of-the-sixth triple in Game 7, Joe Medwick slid hard into Tiger third baseman Marv Owen. They tangled briefly, and when Medwick went back to his position in left field for the bottom of the inning enraged Tiger fans, knowing the game was all but lost (the score was 9–0 by then), vented their frustrations on him, pelting him with fruit, vegetables, bottles and cushions among other things. It was a feat for him to make the catch of a fly ball instead of the orange thrown close to it. Commissioner Landis ordered Medwick out of the game, ending the ruckus. Newsreel footage shows Medwick slamming his glove against the dugout bench in disgust. It was the only time a Commissioner has ejected a player from any major league game, as of 2021^[update].(Audio)

Dizzy Dean nearly took himself out of the Series on a play in Game 4. In the fourth inning, he pinch-ran and broke up a double play the hard way; i.e., by taking the errant relay throw to first flush on the noggin. The great Dean lay unconscious on the field. (He was later to protest, "Hell, it was only a glancing blow.") He was rushed to a hospital for observation, where he was given a clean bill of health. Legend has it that at least one newspaper the next day featured the headline, "X-ray of Dean's head shows nothing." Be that as it may, ol' Diz recovered rapidly enough to start Game 5 (a 3–1 loss to Tiger curveballer Tommy Bridges) the very next day.

According to Charles Einstein's The Fireside Book of Baseball, in the midst of the Cardinals' Game 7 rout, player-manager Frankie Frisch, the "Fordham Flash", called time and walked out to the mound from second base to warn Diz, "If you don't stop clowning around, I'll take you out of the game." Dizzy said, "No you won't." Frisch thought about this a moment, then retreated to second.