Brown was a longtime star with the Negro National League‘s Kansas City Monarchs. He was nicknamed “Home Run” by Hall of Famer Josh Gibson for out-slugging Gibson in their head-to-head confrontations. He began as a shortstop for the Monroe, LA Monarchs, and was later discovered by Kansas City Monarchs owner J.L. Wilkinson. Wilkinson offered Brown a $250 bonus, a $125-a-month salary, and $1 a day as meal money. Brown accepted the increase over his $10-a-week stipend in Monroe.
Brown matured into a complete and dangerous hitter. With Brown batting cleanup, the 1942 Monarchs routinely beat the Dizzy Dean All-Stars in exhibition games played in Chicago and Buffalo. Brown played in the 1942 and 1946 Negro World Series, and hit a combined .304 with three HR and 14 RBI.
Brown became a hero in Puerto Rico by winning three home run and three batting titles from 1946 through 1950, earning the nickname “El Hombre” – The Man. In 1947-48, he won the Triple Crown, hitting .432 with 27 HR and 86 RBI in 60 games.
While leading the NNL with a .372 average in the fall of 1947, the 34-year-old Brown signed with the St. Louis Browns. He became the first black player to hit a home run in the American League. But he felt the St. Louis club was not as talented as the Monarchs: “The Browns couldn’t beat the Monarchs no kind of way, only if we was all asleep. That’s the truth. They didn’t have nothing. I said, ‘Major league team? They got to be kidding.'” After playing only 21 games, and frustrated with a .179 average, he quit the Browns because of racial pressures and the team’s lack of a winning attitude, and rejoined the Monarchs.