[3] Singer, an all round athlete who loved basketball, was discovered by boxing trainers Harry Drucker and Hymie Caplan after his tenth amateur bout which included a great showing in his first outing against the New York State Bantamweight champion, Jimmy Cruze.

Though Singer was young and had stayed far distant from crime, his exceptional winning record caught the eye of the New York mob, who hoped to bring him to a championship as quickly as possible.

In February and March 1929, Singer faced former 1927 world bantamweight champion Bud Taylor at Madison Square Garden, winning in a fourth round disqualification and a ten-round points decision.

[8] In a non-title bout on July 24, 1929, before a crowd of around 29,000, Singer defeated Frenchman Andre Routis, reigning NBA world featherweight champion, in an impressive second-round technical knockout at Ebbetts Field in Brooklyn.

[9][10] On August 29, 1929, Singer lost an important twelve round bout with Black Cuban boxer Kid Chocolate, at the Polo Grounds in New York with 50,000 in attendance.

[11] The decision was unpopular with the New York crowd, who may have been aware that Chocolate effectively blocked a large number of the blows that Singer appeared to land.

[12] Singer captured the World Lightweight Championship on July 17, 1930, before a crowd of 35,000 at Yankee Stadium, with a first-round knockout (1:46) of champion Sammy Mandell.

[6] A Doctor at the scene, who inspected Singer, said the blow may have affected his upper spine and caused a momentary partial paralysis, not uncharacteristic of a knockout.

Coming out of a clinch, Canzoneri threw a left hook to Singer's mouth, and then one to his chin which snapped back his head, and put him down for the count.

[17][18][19] Recovering from his loss of the title on June 18, 1931, Singer defeated Lew Massey before a crowd of 6,395, at Madison Square Garden in a ten-round points decision.

Observing how he threw jabs and punches nearly at will, the Associated Press gave Singer eight of ten rounds, allowing Massey only the seventh when he switched to infighting.

[22] Though Singer started strong very early in the opening round, he was soon put down three times by Battalino, and went down in the second from a series of rights to the chin for a count of seven.

After he rose, he was chased around the ring by Battalino who put him down again with a right to the chin for a count of four, just before the referee justifiably called the bout a technical knockout and helped move Singer to his corner.

Having earned around a quarter million from boxing in his lifetime, Singer tried various businesses in his thirties and forties including sales, restaurants, real estate, and theater, owning several Cabarets.