Often regarded as the greatest British fighter of all time, he was the first official world flyweight champion and was rated by American boxing writer Nat Fleischer, as well as many other professionals and fans including former boxer, trainer, manager, and promoter, Charley "Broadway" Rose, as "the Greatest Flyweight Boxer Ever".

Wilde earned various nicknames, such as "The Mighty Atom", "Ghost with the Hammer in His Hand", and "The Tylorstown Terror" due to his bludgeoning punching power.

[1] Jimmy Wilde's birth certificate states that he was born in the Taff Bargoed Valley community of Pentwyn Deintyr) (now known as the Graig), Quakers Yard, Treharris, Wales, in the county borough of Merthyr Tydfil.

Managed by Teddy Lewis, (reserve captain of the local rugby club, Pontypridd RFC) Wilde went undefeated in 103 bouts, all of which were held in Britain, a remarkable achievement.

In the middle of that streak, on 31 December 1912, he won the British 7 stone championship by beating Billy Padden by an eighteenth-round knockout in Glasgow.

He finally lost his undefeated record when he challenged Tancy Lee for the vacant British and Europe Flyweight Championship on 15 January 1915 in London.

Ignoring his handlers advice to postpone the fight because he was suffering from Influenza, a weakened Wilde was knocked out in the seventeenth round (of twenty).

On 18 December, Wilde became the first World Flyweight Champion when he defeated Young Zulu Kid of the United States, knocking him out in the eleventh round of their bout at the Holborn Stadium.

[5] In late December 1916, after being rejected on two previous occasions due to an old leg problem from a colliery accident and for being underweight, Wilde was accepted into the British Army and while never seeing active service, became a physical training instructor at Aldershot.

Wilde travelled to the United States for a series of fights and on 6 December 1919, lost to "Little" Jackie Sharkey in a controversial ten-round newspaper decision.

[9][10] In 1920, Wilde went undefeated in 10 fights, but lost by a knockout in 17 rounds to former World Bantamweight Champion Pete Herman, who outweighed him by more than a stone (14 pounds), in 1921.

[14][15] In 1927, at the age of 35, Wilde was reportedly considering making a comeback, but after consulting a specialist in head trauma, never returned to competitive boxing.