His managers included Benny Woodhall, Frank Bachman, Hymie Kaplan, and Willie Ketchum and his trainer was Charley Rose.

[2] Jenkins took the World Lightweight Championship on May 10, 1940, in a third-round TKO against Lou Ambers at New York's Madison Square Garden.

[4] On November 21, 1939, Jenkins scored a seventh-round technical knockout against Mike Belloise, a former World Featherweight Champion, before a crowd of 12,000 at the Bronx's New York Coliseum.

[7] On January 24, 1940, Jenkins convincingly defeated Cuban boxer Chino Alvarez in a knockout only around fifteen seconds into the first round at the Sportatorium in Dallas.

Jenkins landed only two or three punches and the rowdy Dallas crowd booed when the ten count was completed, with several climbing into the ring.

When he defeated Tippy Larkin in a first-round knockout at Madison Square Garden on March 8, 1940, he was finally scheduled for a World Lightweight Title bout with reigning champion Lou Ambers.

[11] After winning the World Lightweight Championship from Ambers, Jenkins lost his boxing discipline and spent time carousing at night and buying expensive automobiles.

[3][1][12] On March 8, 1940, Jenkins scored a first-round knockout of Tippy Larkin in a non-title bout at New York's Madison Square Garden before a crowd of 11,542.

On November 22, 1940, Jenkins successfully defended his World Lightweight Title against Pete Lello in a second-round knockout at New York's Madison Square Garden before a largely hostile audience of around 11,000.

[16] Lello had formerly knocked out Jenkins in a close bout that ended in an early seventh round victory in Chicago on March 24, 1939.

[3] On December 19, 1941, Jenkins lost his World Lightweight Title against Sammy Angott before a crowd of 11,343 at New York's Madison Square Garden.

He re-enlisted in the infantry at the outbreak of America's involvement in the Korean War around 1950 and was awarded the Silver Star for saving several men from enemy fire.