He began his professional baseball career in with the Monroe Monarchs, a minor Negro league team. In, he signed with the Kansas City Monarchs, for which he played continuously until seeing action in World War II in 1944–45. During his pre-war baseball years, he established himself as having the most raw power in Negro League history, and possibly in the history of baseball. He hit home runs more often than the better known Josh Gibson, causing Gibson to give Brown his nickname. He also hit for a batting average of.374 in and regularly hitting over.350. Brown was one of the fastest players in baseball in the late 1930s and 1940s, as well as a solid outfielder. From 1937 to 1946 Brown helped lead the Monarchs to six pennants in ten seasons. In the 1942 season the Monarchs met the Negro National League champion Homestead Grays in the first World Series between the Negro American League and the Negro National League. With Brown hitting.412 and a home run, the Monarchs won four straight games.
MLB career
He played briefly in the major leagues in, having signed with the floundering St. Louis Browns. On 20 July, Brown and Hank Thompson played against the Boston Red Sox. It was the first time that two black players appeared in an MLB game together. Brown entered the baseball record books on August 13, 1947, when he became the first African-American player to hit a home run in the American League: an inside-the-park homer off Detroit Tigers pitcher and future Hall of FamerHal Newhouser. Even throughout the season, Brown struggled because of the racism endemic in his new surroundings, as he hit.179 in just 21 games between July 19 and August 21 before he was released.
Later career
That winter, Brown went to Puerto Rico and had one of his greatest seasons ever, batting.432 with 27 home runs and 86 RBI in just 60 games, winning the Triple Crown and earning the nickname Ese Hombre or "That Man". He then won the Puerto Rican Winter League Triple Crown in the 1949–1950 season, and also hit for the cycle once in his career. Returning to the Monarchs for the 1948 season and stayed with the team until his retirement from top-level baseball in. Subsequently, he was a successful minor league player in the Texas League from through. His career home run total is not known, but he is considered to be among the Negro league career leaders in homers despite a relatively brief career.