Fighting out of Liverpool's Rotunda ABC, Bellew claimed both the 2002 and 2003 novice ABA title's by knocking out every man he faced with the exception of Rob Hough who went the whole 3 rounds from Paramount ABC (Stockport) in the under 10 bouts championships. Then, when he was eligible for the Senior championships, he stepped up to the 91 kg heavyweight class and added even more titles to his collection. In 2006 he lost to Danny Price.
Bellew made his professional boxing debut on 6 October 2007 against journeyman Jamie Ambler and made a winning start with a second round win. He followed up the victory with further wins in 2007 over Adam Wilcox, fighting at the Millennium Stadium in Cardiff and Wayne Brooks at the Bolton Arena.
In 2008 Bellew defeated Paul Bonson, Ayitey Powers, Hastings Rasani, Jevgenijs Andrejevs, and Phil Goodwin to take his record up to 8–0. During 2009 he advanced to an unbeaten 12–0 with further wins against the likes of Matthew Ellis, Nick Okoth, Jindrich Velecky, and Martial Bella Oleme.
On 12 March 2010 Bellew challenged for the vacant Commonwealth title at light heavyweight beating Atoli Moore at the Echo Arena in Liverpool. He made his first defence of the title on 24 September 2010 winning a hard fought victory against Bob Ajisafe at the Grosvenor House Hotel in London's Mayfair with Bellew having to recover from a flash knockdown during the fight. He made his second defence of the title on 9 December 2010, returning to the Echo Arena to stop former Commonwealth champion Ovill McKenzie in the 8th round despite suffering two knockdowns himself in the fight in both the 1st and 2nd rounds.
On 18 May 2011 it was announced that Bellew would challenge Nathan Cleverly for the WBO light heavyweight title following a pullout from Cleverly's scheduled opponent Jürgen Brähmer with the fight due to be held only three days later on 21 May 2011. Bellew however, failed to make the weight and was replaced with Polish boxer Aleksy Kuziemski. On 16 July 2011 Bellew made the third defence of his Commonwealth title and also won the vacant British belt with a repeat victory over Ovill McKenzie, with the bout this time lasting the full 12 rounds.
It was announced that Bellew would fight Nathan Cleverly in Liverpool, on 15 October 2011, for the WBO light heavyweight title. For the first two rounds, the fight started at a ferocious pace, with Bellew rocking Cleverly in the second round. As the fight carried on, Cleverly's boxing skills came through to wear down the resistance of Bellew. Cleverly won the fight via majority decision. One judge scored the bout at 114–114 whereas the other two judges scored the bout at 117–112, and 116–113.
After losing to Nathan Cleverly, Bellew took on Danny McIntosh for the vacant British light heavyweight title, knocking McIntosh out in the 5th Round. Next he took on former World title challenger Edison Miranda for the WBC International belt, and stopped Miranda in the 9th Round.
On 17 November 2012 he beat Argentine Roberto Bolonti for the WBC silver title. Bellew was cut badly but went the full 12 rounds to a win unanimous decision, taking him one step further to a second world title fight. On 30 March 2013, he fought Malawian boxer Isaac Chilemba in a title eliminator. Bellew started very well, but Chilemba raised his game in the later rounds. Although many felt Bellew had done enough to secure a points decision, the judges scored it a controversial draw. Chilemba granted a rematch which Bellew won on the scorecards after 12 round, with scores of 116–112, 116–112, and 117–112.
Bellew was made Mandatory Challenger for the WBC light heavyweight title following the win against Chilemba. However, a fight between Adonis Stevenson and Tavoris Cloud occurred on 28 September 2013 with the winner being made to defend his title against Bellew before the end of the year. Stevenson became the first boxer to stop Bellew winning the fight via TKO. In round 6, Stevenson put Bellew down with a left hand, he beat the count and the referee let the fight go on. Bellew was then knocked out standing by another pair of left hands before the referee could get in and put a stop to the bout. At the time of stoppage, Stevenson was ahead on the scorecards 50-45, 49-46, 50-45. Bellew contemplated moving up to cruiserweight after the loss. According to Nielsen Media Research firm, the fight attracted an average of 1.3 million viewers on the HBO network, making it the 5th most watched bout of 2013.
Bellew celebrated his first fight as a Cruiserweight with a 12th-round knockout of Valery Brudov on 15 March 2014 at the Echo Arena, Liverpool. This was for the vacant WBO International Cruiserweight title. Bellew successfully defended the title on 12 July 2014 against Julio Cesar Dos Santos via a 5th-round TKO. Dos Santos went down following a left to the jaw.
On 22 November 2014 Bellew got his rematch against Nathan Cleverly, this time fighting as cruiserweights. The fight took place at the Echo Arena in Liverpool also a WBO cruiserweight championship eliminator. The title was held by Marco Huck at the time. The bout went 12 rounds as Bellew won via split decision 115–113, 116–112, and 114–115. In the post-fight interview, Bellew said, "I’m over the moon, listen it’s over, it’s put to bed. We said a lot of things. I don’t like him now, but it’s been settled tonight. It’s over, it’s done and I've outworked a great athlete." He also stated that he would do a rubber match at Millennium Stadium if there was any demand for it. Cleverly said he struggled with dealing with Bellew at a higher weight. After the fight, Cleverly moved back down to light heavyweight.
In 2015, Bellew fought two lower ranked European boxers. He defeated Ivica Bacurin via 10th-round TKO, Arturs Kulikauskis via 5th-round TKO.
In December, Bellew faced highly ranked Polish contender and former world title challenger Mateusz Masternak (36-3, 26 KOs) for the vacant European Cruiserweight title. Bellew produced a solid performance as the fight with Masternak was back and forth throughout. Going into the 12th round, Bellew was winning by one round. Bellew rocked Masternak late in the round badly but was unable to finish him. However, he won the fight via unanimous decision 115–112, 115–112, and 115–113 to capture the European championship.
On 29 May 2016, Bellew challenged for the WBC cruiserweight title, vacated by Grigory Drozd, who had been injured and not fought since his knockout win in May 2015. Bellew faced Ilunga Makabu (19-1, 18 KOs), who had not lost since his debut back in 2008, at Goodison Park in Liverpool. Makabu was scheduled to fight Drozd, only for the Russian to pull out with an injury, prompting the WBC to strip him. Bellew weighed in at 14st 3lbs 1oz while Makabu took to the scales at just over 14st. Bellew overcame a first-round knock-down to deliver a thunderous knockout of Makabu and become WBC cruiserweight champion, winning his first world title. During the post-fight interview, Bellew called out Denis Lebedev, but not in Russia and David Haye at cruiserweight.
Bellew announced he would be making his first voluntary defence of his world title at the Echo Arena on 15 October, against 37-year-old American boxer BJ Flores (32-2-1, 20 KOs) live on Sky Sports. This was the first time Flores challenged for a world title, having previously fought for an interim title and the IBO title. The WBC stated the winner had to fight Mairis Briedis next, the mandatory challenger, following his win over Olanrewaju Durodola. Briedis also fought on the undercard stopping unbeaten British prospect Simon Vallily. Mairis Briedis agreed to take a step a side fee to allow this fight to take place.
After an even first round, the second round proved to be brutal as Bellew hit Flores on the belt. The referee did not see this as below the belt, however, Flores stopped for a few seconds to motion the referee that he had been hit with a low blow. Whilst doing so, Bellew piled on more pressure, eventually knocking Flores down. Bellew knocked Flores down a further two times in round 2 securing a 10-6 round in his favour. After a fourth knockdown in round three, Flores failed to beat the referee's count declaring Bellew the winner via knockout and making a first successful defence of the WBC world title. Following the win, Bellew immediately hit out a verbal assault on rival David Haye, who was ringside, repeating that he was next. Referring to Haye as 'SpongeBob', Bellew carried on the verbal assault in the post-fight interview using profanity and taunting Haye, stating he has been 'conning the British public' since he announced his comeback. Eddie Hearn claimed the fight could take place at heavyweight or at cruiserweight for Bellew's WBC title.
On 25 November 2016, Eddie Hearn announced via Twitter that Bellew's next fight would be against fellow Briton and former WBA heavyweight champion David Haye. The fight date was set for 4 March 2017 at The 02 arena, London and was shown on Sky Box Office and was Bellew's first heavyweight fight. Due to the fight being at heavyweight, Bellew's WBC cruiserweight title was not on the line.
At the first press conference on 30 November, a fight broke out as Bellew and Haye went face to face and it appeared on the replay, Haye had managed to land a left hook on Bellew, leaving a mark. Both fighters were then separated before going their own ways. On 3 March 2017, Haye weighed 224.9 pounds, heavier than Bellew who came in at 213lbs, a career high. The bout started as a stalemate until the sixth round, where Haye injured his ankle and fell down twice. Bellew then took control of the fight as Haye opted to continue. Bellew knocked Haye down out of the ropes late in the eleventh round. Haye managed to make it to his feet, but his trainer Shane McGuigan threw in the towel, giving Bellew a TKO win. Bellew credited Haye for his bravery, while Haye refused to blame his injury and stated that Bellew was "by far the better fighter", though stated that he wanted a rematch. Bellew contemplated retiring after claiming he had done it all. He also revealed he broke his hand in the early rounds. At the time of stoppage, Bellew lead on all three scorecards 96-93. With a 60-40 split of the £7 million purse, Haye earned £4.2 million while Bellew earned £2.8 million, his biggest purse by far. It was reported that the fight generated 890,000 buys on Box Office PPV.
On 14 March, Hearn said that Bellew would fight again in 2017, a day later, he told Sky Sports that Bellew may need surgery on his broken hand which could see him out of action for up to five months.
On 28 March, WBC changed Bellew's world championship status to Emeritus champion. This also meant the winner between Marco Huck and Mairis Briedis on 1 April would become new world champion and not Interim, as it was initially announced. The bout was won by Briedis, thus making him the new WBC champion.
In June 2017, Bellew stated that he would next fight in either November or December of 2017. He had three potential names to consider, those being WBO champion Joseph Parker, WBC champion Deontay Wilder and a rematch with David Haye. Parker being the main interest.
In July 2017, Bellew admitted that a potential fight with widely regarded pound for pound number one fighter and unified light-heavyweight champion Andre Ward was of interest and the teams of the respective fighters were currently in negotiations. On 3 August, Hearn stated a rematch between Bellew and Haye was 'virtually dead', due to both fighters believing they are the A-side and have the right to demand ring walks, poster, changing rooms and split of purse. On 6 September, Hearn stated a deal could be made within seven days. According to trainer David Coldwell, both Haye and Bellew had held positive talks and looking more likely to agree to a fight, as long they stay on the same page and agree to the same terms. On 19 September, Haye agreed all the terms and tweeted Bellew to sign the contract. He said, "It's taken months of negotiating but teams have finally agreed all terms for Haye-Bellew 2. Will Bellew put pen to paper?" The fight was reported to take place on Sunday 17 December 2017. Promoter Eddie Hearn stated the fight was not a done deal, but he had hoped to confirm the fight within a week. Bellew replied the following day, tweeting, "I OBLIGE YOU @mrdavidhaye , happy? Now leave me alone with my family please. I'll see you soon enough!"
Bellew is biracial; his mother is black. He has three sons and lives with his girlfriend, Rachael, in Aughton, Lancashire.
Bellew is an avid supporter of Everton FC, and has been paraded on the Goodison Park pitch at half-time during a game. He enters the ring to the theme from Z-Cars, the same song that the players enter the pitch to during matches at Everton's home ground (Goodison Park).Creed (2015) as "Pretty" Ricky Conlan