One interesting fact of his life is that Lewis was managed by a gambler and racketeer of the 1930s: Gus Greenlee, a man who became very important to baseball's Negro leagues as a commissioner and team owner.
Lewis began his professional career in 1928, beating Buster Grant by a four round decision, in Phoenix. His first 14 fights were in that city, until 1931, when he travelled to Prescott, to fight Sam Terrain on March 11. This proved to be a tragic event, as Terrain died as a consequence of the blows received during Lewis' fourth round knockout win.
Lewis had nine more wins in a row before facing future word Heavyweight champion, The Cinderella Man, James J. Braddock. He beat Braddock by a ten round decision, but, after two more wins, on November 16, 1932, he lost for the first time, to fellow world Light Heavyweight champion Maxie Rosembloom, by a decision in ten.
Lewis fought four more times, winning three and drawing one, before getting a chance at avenging his loss to Rosembloom in 1933, and he won a 10 round decision in their rematch, and again in their third match.
In 1934, Lewis had 12 bouts, going 9-1-2 in that period. He tried to win the Pacific Coast Light Heavyweight title, drawing with Young Firpo in ten rounds, and he lost in a rematch with Braddock, by decision.
In 1935, Lewis won nine bouts in a row, including one by decision over world Light Heavyweight champion Bob Olin. Ironically, after he lost two bouts in a row, he was given a chance at the world's Light Heavyweight championship by Olin. On Halloween night of that year, in St. Louis, Lewis became the world's Light Heavyweight champion by outpointing Olin over 15 rounds.
In his next fight, he lost to Rosembloom in a 10 round, non-title bout by decision.
In 1936, Lewis had 20 fights, going 18-1-1 that year, but only two of those were world championship bouts. He retained his belt against Jock McAvoy and Len Harvey, the latter of which was defeated at London. Lewis won both title defenses by decision in 15 rounds.
1937 was another busy year for the world's Light Heavyweight champion, with 20 more fights and a record of 18-2 that year. Standing out that year were his two fights against Al Ettore, of which in the first, fought over ten rounds, Ettore was declared the winner but the Pennsylvania boxing commission changed the official decision to a draw, and in the second, he beat Ettore by a decision in 15, following with his eight round knockout of Olin to defend the title, and his non-title win over Johnny Risko.
In 1938, he fought 12 times, going undefeated, retaining the title against Emilio Martinez by a knockout in round four, and against Al Gainer, by decision in 15.
Lewis tried, in 1939, to become the first Light Heavyweight champion in boxing history to go up in weight and conquer the world's Heavyweight championship. On January 25, he was faced with world Heavyweight champion Joe Louis, who knocked him out in the first round in New York. This would turn out to be Lewis' last fight, even through he didn't know it at the time.
His next fight would have been a rematch with Len Harvey in London, but Lewis did not pass the medical tests before the fight, and the fight was cancelled, so in June of that year, he announced his retirement.
Lewis had a record of 103 wins, 9 losses and 6 draws, with 60 wins by knockout. His 60 knockout wins makes him a member of boxing's exclusive club of winners by knockout 50 or more times.
Lewis is a member of the International Boxing Hall of Fame.