Jeffries was born in Sunderland, Tyne and Wear and grew up around the East Herrington area of the city whilst attending Farringdon Community Sports College.

[11] At the 2007 World Amateur Boxing Championships he beat Daniel Kooij, Christopher Downs and Ramazan Magomedov in the preliminaries, but lost to Kazakhstan southpaw Yerkebuian Shynaliyev in the quarters.

[12][13][14] Jeffries signed his first professional contract during the half-time break of Sunderland's match against the Bolton Wanderers on Saturday 29 November, after a row over unpaid bonuses from the Amateur Boxing Association of England.

On 27 February, Jeffries won his debut fight at super middleweight on the Munroe-Martinez undercard in a first-round knockout of Aliaksandr Vaiavoda in Barnsley.

Jefferies and his fellow trainer left this gym and started a boxing bootcamp in Santa Monica which received investment from actor Mickey Rourke.

[17][18][19] The terms of the premises were changed by Mickey Rourke, contrary to what Jeffries and the other trainer originally agreed upon so they went separate ways.

Alongside his ventures in boxing, Jefferies played a role in NBC TV's Blacklist in 2013 and was one of the figures in Levi's world campaign in the same year.

Jeffries has taken up Brazilian jiu-jitsu since retiring from boxing and in 2024 he had first competition, winning a gold medal in a white belt masters division.