The 1934 major league baseball season began on April 17, 1934. The regular season ended on September 30, with the St. Louis Cardinals and Detroit Tigers as the regular season champions of the National League and American League, respectively. The postseason began with Game 1 of the 31st World Series on October 3 and ended with Game 7 on October 9. The Cardinals then defeated the Tigers, four games to three.
The 1934 schedule consisted of 154 games for all teams in the American League and National League, each of which had eight teams. Each team was scheduled to play 22 games against the other seven teams of their respective league. This continued the format put in place since the 1904 season (except for 1919) and would be used until 1961 in the American League and 1962 in the National League.
Opening Day, April 17, featured all sixteen teams, the first since the 1931 season. The final day of the regular season was on September 30, which also saw all sixteen teams play, continued the trend which began with the 1930 season. This was the second time that both Opening Day and the final day of the season saw all sixteen teams play, the previous being in 1931. The World Series took place between October 3 and October 9.