Also known as "Black Mike," Cochrane was educated at Boston University, where he played five sports. He broke in with the Philadelphia Athletics in 1925 as the team's starting catcher, quickly establishing himself as one of the best offensive players ever at the position. A left-handed batter, Cochrane ran well enough that manager Connie Mack would occasionally insert him into the leadoff spot in the batting order. Most frequently, Cochrane would bat third, but wherever he hit, his primary job was to get on base so that hard-hitting Al Simmons and Jimmie Foxx could drive him in.
Known for his fiery temper, Cochrane and teammate Lefty Grove were known to tear up locker rooms after difficult losses.
Cochrane enjoyed his best year in 1930, when he hit .357 with 10 home runs and 85 RBI and scored 110 runs. He played in three World Series with the Athletics, and was blamed by many for the loss of the 1931 World Series against the St. Louis Cardinals, who, led by Pepper Martin, stole eight bases in the series, five of those by Martin.
In 1934, Connie Mack started to disassemble his dynasty and sold Cochrane to the Detroit Tigers, who made him player-manager. Cochrane led the Tigers to the World Series in 1934 and 1935.
Cochrane's playing career came to a sudden end on May 25, 1937 when he was hit in the head by a pitch by Yankees pitcher Bump Hadley. Hospitalized for seven days, the injury nearly killed him. Ordered by doctors not to play baseball again, Cochrane returned to the dugout but he lost his fire. He managed for the remainder of the 1937 season and was replaced midway through the 1938 season.