[5][6] Turning professional around April 1909, in September of that year, he competed for the Southern Bantamweight title in Atlanta, Georgia, drawing with George Kitson in a ten round decision.

[5] Future world lightweight champion Charley White fell to Mandot in an eight round points decision at Memphis's Southern Athletic Club on April 17, 1911.

Allen was floored seven times, and was badly punished in the fifth, sixth, and seventh rounds, dispensing staggering swings to the head and body.

Mandot was down for a long count in the second, but carried the fight to the Englishman for the remainder of the match, scoring a comfortable lead in points by the eighth.

[11] On June 24, 1912, Mandot drew with future holder of the world lightweight championship, Willie Ritchie, in a ten round newspaper decision in New Orleans.

[5] Mandot defeated Mexican Joe Rivers on September 2, 1912, in a twenty round points decision at the Arena in Vernon, California.

The fighting was fast and fierce, but Rivers appeared to win decisively, landed more frequent and telling blows and taking the lead in most of the rounds.

[15] He contended for the world lightweight title against Ad Wolgast on November 4, 1912, drawing in a ten round newspaper decision in New Orleans.

[16][5] Mandot lost in a close bout to future lightweight champion English boxer Freddie Welsh on May 25, 1914, in a ten round newspaper decision at Pelican Stadium in New Orleans.

The Los Angeles Times wrote that Mandot deserved the decision and that he had Callahan close to a knockout in the sixth, seventh, and eighth rounds, staggering him repeatedly.

[21] On October 26, 1915, he contended for the world welterweight championship against British Jewish boxer Ted "Kid" Lewis, losing in a twelve round points decision at the Arena in Boston.

[22] Mandot fell to the incomparable future world lightweight champion Benny Leonard on December 17, 1915, in a seventh round knockout in New York.

Never one to shrink from the toughest competition, The York Times wrote that the match, "was a brilliant display of scientific boxing and hard punching for the first six rounds".

[5] When Mandot rushed in the seventh, Leonard's straight left followed by a right cross to the jaw nearly ended the skillfully fought battle.

[25] He lost to the less experienced Pal Moran on December 2, 1918, in a fifteen round points decision at the Tulane Arena in New Orleans.

He had drawn with Moran in a fifteen round points decision on July 15, 1918, at the Tulane Arena in a bout that was billed as a "Southern lightweight championship" and used a three judge system.