At the Championships, Campbell defeated Olympic bronze medalist Veaceslav Gojan of Moldova in the quarterfinals and Denis Makarov of Germany in the semifinals before facing the experienced Detelin Dalakliev of Bulgaria in the final.

On the Saturday Luke, who convincingly won his Featherweight (57 kg) fight by an 11–5 points margin over China's Jun Tan at the WBC Night Of Champions,[5] continued his winning ways by beating Kazakhstan's Shulakov Madi by 6 – 4 in the semi-final of the Four Nations Challenge.

In Sunday's final Luke again faced Jun Tan from China, his adversary the previous week at the WBC Night of Champions.

At the 2012 London Olympics, Campbell won gold in the 56 kg Bantamweight division after beating Ireland's John Joe Nevin 14:11.

In the quarter-finals he met Detelin Dalakliev of Bulgaria in his closest bout of the competition, controversially[citation needed] edging it by a score of 16:15.

His next opponent, Satoshi Shimizu from Japan- who had earlier been reinstated in the tournament by AIBA after a successful appeal after a defeat by Magomed Abdulhamidov was beaten by 20:11.

Campbell beat Nevin in the final bout, and dropped the Irishman at the start of the third round, thus becoming the first bantamweight boxer to win Olympic gold for Great Britain since Henry Thomas in 1908.

[15] In April 2014, Campbell announced that he would be taking a break from boxing, pulling out of his next scheduled bout, following his father being diagnosed with cancer.

On 1 August, Campbell claimed the vacant WBC International lightweight title by defeating fellow Hullensian Tommy Coyle (21–2, 10 KOs) via ten-round TKO at the KC Lightstream Stadium.

[17] Only four months later in December, Campbell lost the title and mandatory status in a split decision loss to French boxer Yvan Mendy (32–4–1, 16 KOs) at The O2 Arena in London on the undercard of Anthony Joshua vs. Dillian Whyte.

[19] Campbell made a winning return to the ring in spectacular fashion only needing two rounds to finish Sykes off in his first fight since losing his unbeaten professional record.

[20] Promoter Eddie Hearn revealed Campbell was next due to fight on 30 July 2016 at the First Direct Arena in Leeds for the vacant WBC Silver lightweight title against 30 year old former IBF junior-lightweight champion Argenis Mendez (23–4–1, 12 KOs).

[21] Although being floored by a sharp right hand in the second round, Campbell proved to be too quick and dominated the remainder of the fight to claim the vacant WBC Silver lightweight title.

[22] Campbell fought former British and Commonwealth lightweight champion and former world title challenger Derry Mathews (38–10, 20 KOs) on the undercard of the world cruiserweight title fight between Tony Bellew and BJ Flores at the Echo Arena on 15 October, live on Sky Sports.

[25] On 3 January 2017, it was announced that Campbell would defend his WBC Silver title against Jairo Lopez (21–6, 14 KOs) at the Ice Arena in Hull on 25 February.

[31][32] Golden Boy Promotions matchmaker, Robert Diaz, announced that WBA and The Ring lightweight champion Jorge Linares (42–3, 27 KOs) would next fight on 23 September 2017 and ruled out Campbell as his opponent.

As per WBA rules, a titleholder must fight a mandatory within nine months, this time would expire on 23 July, having won the title from Crolla in September 2016.

[36][37] In front of 4,125, Linares won his twelfth straight fight, retaining his WBA world title after twelve rounds against Campbell.

In the following round, Campbell started to unload and landed a barrage of unanswered punches before the referee stepped in to stop the fight.

[45] On 6 August, Sky Sports announced the rematch between Campbell and 33 year old French boxer Yvan Mendy (40–4–1, 19 KOs) was confirmed to take place on the Anthony Joshua vs. Alexander Povetkin undercard at the Wembley Stadium in London on 22 September.

Mendy had his moments in the earlier rounds, but once Campbell adjusted, he was able to box and move to pound out a decision victory in what was a WBC lightweight title eliminator.

[49][50][51] On 15 March 2019, Campbell, who was now the mandatory challenger to Mikey Garcia's WBC lightweight title, travelled to Philadelphia, Pennsylvania, to take on Adrian Yung.

[52] On 31 August 2019, Campbell challenged the top pound-for-pound fighter and three-division world champion, Vasiliy Lomachenko, for the WBA (Super), WBO, The Ring, and vacant WBC lightweight titles at The O2 Arena in London.

[53] Prior to the fight on 22 August 2019, Sky Sports released "The Gloves are Off: The Debate (Lomachenko vs. Campbell)" segment, hosted by former cruiserweight world champion Johnny Nelson, with retired, former world champions Tony Bellew, Carl Froch, David Haye and Paulie Malignaggi giving their pre-fight analysis as part of the lead up to the fight.

"[54] On the night of the fight, Lomachenko put on a dominant display, dropping Campbell in the eleventh round and winning a wide unanimous decision with scores of 119–108, 119–108, 118–109.

[53] On 2 January 2021, Campbell faced undefeated Ryan García for the vacant WBC interim lightweight title in what would ultimately be his final professional fight.

Despite entering as the pre-fight betting underdog, Campbell dropped his opponent in the second round with a left hand, from which García recovered.

He released a statement on Twitter, saying, "Every fight, right the way from my debut on 13th June 2013, up to my last on 2nd January 2021, the cheers and messages of encouragement have always been monumental.

[60] In December 2012 it was announced that Campbell would take part in ITV's Dancing on Ice series 8 which started on 6 January 2013, skating with professional Jenna Smith.