As of May 2017, Frampton is ranked as the world's second best featherweight by BoxRec and the Transnational Boxing Rankings Board, and third by The Ring magazine.
Amateur boxing in both the Republic of Ireland and Northern Ireland is governed by the Irish Amateur Boxing Association. As an amateur, Frampton fought out of the Midland Boxing Club in Tiger's Bay and won the Irish senior flyweight title in 2005 and added the Irish featherweight title in 2009, beating David Oliver Joyce in the final.
He also claimed a silver medal at the 2007 European Union Amateur Boxing Championships in Dublin, losing to France's Khedafi Djelkhir in the final. Frampton is one of Ireland's most successful amateur boxers of recent years, winning over 100 of his fights and losing only 8 times.
Later commenting on his decision to box for the Irish team, Frampton, who grew up in a Unionist area of Belfast, said "I get asked all the time, 'would you have liked to have boxed for Great Britain?' And the answer is 'no'. I was looked after by Irish boxing from pretty much 11 years old and was very proud to box for Ireland." He added, "it's very humbling to know that so many people are supporting me from all over Ireland and mainland UK."
Frampton turned professional after his victory in the 2009 Irish featherweight finals. In June 2009, fought his first professional fight at the Olympia, Liverpool, in England and beat Sandor Szinavel with a second-round knock-out on a card that included Grzegorz Proksa and Ajose Olusegan. In January 2010, he was named Ireland's Prospect of the Year at the Irish National Boxing Awards. In September 2010 he recorded an "electrifying" win over the Ukrainian Yuri Voronin in front of an Ulster Hall crowd which included Daniel Day-Lewis. The win led the Belfast Telegraph to liken him to a "reincarnation" of Barry McGuigan.
In December 2010, Frampton won his first professional title, the BBBofC Celtic Super Bantamweight title, with a second-round TKO win over Scottish boxer Gavin Reid in the Ulster Hall. Following his victory, Frampton described the Super Bantamweight division as being "super-hot" and named Scott Quigg and Rendall Munroe as potential opponents. He then went on to get a fourth-round TKO win over Venezuelan Oscar Chacin, and later fought his first defence of his BBBofC Celtic title against Welshman Robbie Turley in June 2011, winning by a unanimous decision after ten rounds.
Carl fought Australian Mark Quon as a replacement for Kiko Martinez on 10 September for the Commonwealth Super Bantamweight title at the Odyssey Arena in Belfast winning by a fourth-round TKO stoppage. On 28 January 2012, he successfully defended his Commonwealth title against Kris Hughes in the York Hall, with the fight having to be stopped in the seventh round. According to the BBC, Frampton controlled the contest from the start and was never threatened by his opponent. On 17 March 2012, Frampton once again defended his title against Ghana's Prosper Ankrah and won by a second-round TKO stoppage. After his victory Frampton challenged the British Champion Scott Quigg saying that "I don't know if he wants it but, if he does, he should tell his promoter".
Frampton then beat fellow unbeaten contender Raúl Hirales, Jr. (previously 16-0, 8 KO's) of Mexico by a unanimous decision and won the vacant IBF Inter-continental Super Bantamweight title on the undercard of Carl Froch vs. Lucian Bute in Nottingham, UK. The fight took place on 26 May 2012. On 22 September 2012, Frampton took on former two-time world champion Steve Molitor. The fight took place in the Odyssey Arena in Belfast on a card that included Martin Lindsay and Paul McCloskey. Frampton scored an impressive sixth-round TKO and had the former champion on the canvas three times during the bout. After the fight, Frampton announced that he was willing to "fight anyone" and that he was "ready for a world title fight".
On 9 February 2013, Carl Frampton faced hard-punching Spaniard Kiko Martinez in front of 8,000 of his home fans in the Odyssey Arena in Belfast. Martinez, the European Champion, had previously knocked out Bernard Dunne in 86 seconds to win the title and had never been knocked down. Frampton won by TKO in Round 9, winning the European Super Bantamweight title and retaining the IBF Inter-Continental Super Bantamweight title. After the fight Frampton said "I just want the people of Belfast to be proud of me", and described his beaten opponent as "hard as nails". In August 2014, Martinez won the IBF title with a sixth-round stoppage of the previously unbeaten Colombian Jonatan Romero.
On 19 October 2013, Frampton defended his EBU and IBF Inter-Continental titles in an IBF World Title Eliminator against IBF #4 ranked Jeremy Parodi. The fight took place in front of a maximum capacity 9,000 fans at the Odyssey Arena, Belfast. Frampton knocked Parodi out with a body shot at the end of the sixth round. On 4 April 2014 Frampton faced the Mexican Hugo Cazares at the Odyssey Arena in a final eliminator for Leo Santa Cruz's WBC Super Bantamweight World Championship. In front of a sold-out crowd of 9,000 Frampton knocked out Cazares in the 2nd Round, with a left hook to the head.
Frampton challenged for his first world title on 6 September 2014 in a rematch against Kiko Martinez (31-4, 23 KOs). Martinez's IBF Super Bantamweight title was at stake and the bout took place in an outdoor arena at the Titanic Quarter in Belfast. In the build-up to the fight, Frampton said of Martinez: "He's very emotional and that's what makes him dangerous... he's a hot-head, he can be very easily agitated but he's coming to win". Fighting in front of a crowd of 16,000 Frampton knocked Martinez down in the fifth round and won by unanimous decision, with two scores of 119-108 and one score of 118-111, winning his first world title. Interviewed after the fight Frampton said "I've got the world title. I feel a bit emotional – it has been a long time coming, it has been a hard road. I intend to hang on to it for a very long time." He went on to call for a unification fight with the WBA champion Scott Quigg, saying "I'll fight him in Manchester, I'll fight him anywhere". After the fight, Barry McGuigan said of his protege "This kid could end up as the best Irish fighter there has ever been."
As result of his performances Frampton was nominated for the 2014 RTE Sports Person of the Year. In 2015, he was named Britain's Coolest Man by ZOO Magazine beating the likes of David Beckham, Tom Hardy and Ed Sheeran to get the award. Frampton said after receiving the award, "I couldn't believe it when they told me, I thought it was a wind-up! But it's great, especially as it's ZOO readers and the people of Britain who have voted for me. It's also great for the sport of boxing."
Frampton was appointed Member of the Order of the British Empire (MBE) in the 2016 New Year Honours for services to boxing.
Frampton made his first defence on his title on 28 February 2015 against American Chris Avalos (25-2, 19 KOs) at the Odyssey Arena in Belfast, Northern Ireland. Frampton made a successful defense of his world title in devastating fashion as he laid a sustained beating on Avalos en route to a one-sided, fifth-round knockout. Avalos took a ferocious beating in the fifth round. A clean right hand staggered Avalos as Frampton continued to pound him around the ring. When he rocked Avalos with another right hand, referee Foster intervened and waved off the contest at 1 minute, 33 seconds.
It was announced that Frampton would make a second defence of his IBF World title on July 18 at the Don Haskins Convention Center, El Paso, Texas against 22 year old Alejandro Gonzalez Jr live on ITV. Gonzalez, who was a massive underdog, scored two knockdowns in the first round and appeared to ruin Frampton's plans. Frampton shook off the knockdowns, came back strong and rolled to a decisive unanimous decision in a highly entertaining fight that headlined the Premier Boxing Champions card on CBS. Despite the anxious early moments, Frampton won 116-108, 116-108 and 115-109 on the scorecards. Referee Mark Calo-Oy warned Gonzalez for hitting Frampton with a low blow in the second round and then took away a point when he did it again in the third round. Frampton controlled the fight from there on. According to CompuBox punch statistics, Frampton connected on 246 of 692 blows (36 percent), whilst Gonzalez landed 145 of 593 (24 percent).
On 27 February 2016, Frampton fought his long-awaited opponent, undefeated WBA super-bantamweight champion Scott Quigg (31-0-2, 23 KOs) in front of a sell out crowd in Manchester. In a close fight, Frampton won by split decision with the judges scoring the fight 113-115, 116-112, 116-112. Frampton was in full control of the first half of the fight, during which Quigg simply could not find his range, however Quigg finally came alive down the stretch as the contest turned into a desperate tussle, but Frampton gave as good as he got.
In March 2016, several press releases announced that Frampton did not intend to face Rigondeaux in his next bout. On 11 March 2016 the WBA wrote to Frampton inquiring whether the press releases were accurate and requested he confirm his intentions on or before 18 March 2016. The WBA received no response. Additionally, Rigondeaux's representatives were not approached by anyone on Frampton's behalf to negotiate a bout. "In light of Frampton's announced intention to face an opponent other than his mandatory", says WBA Championships Chairman Gilberto Jesus Mendoza, "and for failing to respond to WBA inquiries as to his intent, Frampton's recognition as Champion is removed."
Frampton moved up a weight class to fight undefeated Mexican Léo Santa Cruz (32-0-1, 22 KO's) for the WBA (Super) Featherweight title at the Barclays Centre in New York City on 30 July 2016. In a potential fight of the year candidate, Frampton became the first two division world champion in the history of Northern Ireland as he dethroned Santa Cruz via a 12-round majority decision win before an crowd of 9,062. One judge scored it a 114-114 draw but the others made Frampton the winner, 116-112 and 117-111. Frampton had a higher accuracy rate, despite both fighters landing equal amount of punches. According to CompuBox stats, Frampton landed 242 of 668 punches (36 percent), whilst Santa Cruz connected on 255 of 1,002 blows (25 percent). In the post fight, Frampton said he wanted to defend the title in his home city and did not want to rule out a rematch. Frampton vowed to break records and become the first Irishman to win world titles at three different weights. The fight averaged 480,000 and peaked at 549,000 viewers.
As discussed immediately following the first bout, a rematch between Frampton and Santa Cruz was finalised in October. There was talks the fight would take place in Frampton's hometown of Belfast, however the venue was confirmed to be at the MGM Grand in Las Vegas, the first time Frampton would fight there since becoming a professional. The date was confirmed to be 28 January 2017. 10,085 were in attendance as Frampton lost his title by majority decision. Santa Cruz and Frampton immediately discussed interest in a third fight, possibly in Frampton's hometown of Belfast. Frampton earned a purse of $1 million compared to $900,000 that Santa Cruz received. Frampton only landed 133 of his 592 punches thrown (22%) whereas Santa Cruz landed 230 of his 884 thrown (26%). Nielsen Media Research reported the fight averaged 587,000 and peaked at 643,000 viewers.
On 14 May 2017, Frampton was number two by the WBA at super featherweight, which indicated to many that he may be moving up to become a three-weight world champion. By the end of May, talks had begun for a fight against IBF champion Lee Selby. Frampton's promoter Barry McGuigan said the fight would happen, but may not happen next due to Selby having a mandatory fight due next. On 15 June, Frampton labelled Selby a 'time-waster' and announced that he would be returning to the ring in Belfast on 29 July against an unnamed opponent. Cyclone Promotions confirmed that Frampton would fight 23 year old Mexican boxer Andrés Gutiérrez (35-1-1, 25 KOs) at the SSE Arena in Belfast in a WBC eliminator. A day before the fight, Frampton weighed one pound over the 126 pound limit. The was to still take place but without being an eliminator. Frampton apologised to his fans in a statement,
"After a long training camp of intense preparation and trying to make weight, I was disappointed that I came in 1lb over the featherweight limit today. I tried everything I could to cut down, but unfortunately, my body just wouldn't allow it in the end. I'd like to apologise to the fans that have got involved and shown incredible support throughout this frantic fight week, and to those that will be cheering me onto victory on Saturday night. Furthermore, I would like to apologise to my opponent Andres Gutierrez - who will still have the opportunity to win the WBC eliminator on Saturday."
Later that day, Gutiérrez slipped in the shower in his hotel and suffered a gash on his chin. It was also reported that he had knocked some teeth out in the process and bruised his head. The fight was called off. Frampton's manager Barry McGuigan was said to be disappointed, but told ticket holders to retain their tickets as the card could be rescheduled. Cyclone Promotions, together with The SSE Arena and the Gutiérrez camp said they would work quickly to reschedule the fight and find a new date.
On 17 August 2017, the fight was called off completely. The news came after reports circulated that Frampton would be parting ways with long time promoter Cyclone Promotions. A date in November was considered, however was unsuitable for both boxers. Frampton officially announced the split with Cyclone Promotions on 22 August 2017. In the tweet, he had no mention to whether he would still train with Shane McGuigan.
In early September, rumours circulated that Frampton would hire former boxer Jamie Moore as his new trainer. On 6 September, Frampton confirmed the rumours on his Twitter as being true as he officially revealed his new trainer. On 19 September, Frampton announced he had signed a deal with MTK Global, who would work on his behalf as advisors. On 23 September it was rumoured that Frampton would sign with British promoter Frank Warren. After splitting with Cyclone, Frampton made it known that he would only sign with a promoter who could guarantee him a stadium fight Ireland. A day later, Frampton revealed he had joined Warren. In a statement, he said, "I had interest from America and the UK but it really came down to two very similar offers from Eddie Hearn and Frank Warren. I'm desperate to kick on and have a fight before Christmas and I can confirm I will be fighting in Belfast." He wanted to secure a world title in the first half of 2018.
Hailing from Belfast, a city known for its troubled history, Frampton wants to be remembered like Barry McGuigan, his manager, who was seen as a symbol of peace during his fighting days. Despite being from the Republic, it was Northern Ireland where McGuigan's fights had most significance, unifying the people there despite the religious and political differences that existed between them.
"I want to be a legend," Frampton said in 2015. "Honestly, that's what I want to be, a legend in Irish sport. I think it's coming up to 30 years since Barry won his world title in Loftus Road against Pedroza and people are still talking about it. I want to be like that 30 years from now – people are talking about my fights with guys like Chris Avalos and Kiko Martinez in the pubs all over Ireland. That's what I intend to do. I want to create a legacy. I want to keep beating big names. I want to get big fights, bring them back to Belfast as much as possible, and keep winning." Speaking to the BBC, McGuigan said "Carl is doing what I did. He's a beacon for peace and reconciliation and represents the future of Northern Ireland."
In 2014, he claimed Frampton "could end up as the best Irish fighter there has ever been. He can go to featherweight and super-featherweight. I don't know who the greatest Irish fighter is but if he gets the right fights he can really go as far as he wants to go." As a fighter, McGuigan was known for wearing a Dove on his shorts, as a representation of peace. He also had no national anthem played at his fights, he took up dual Irish-British citizenship which allowed him to fight for British Domestic titles, and he married a Protestant woman, all of which had huge significance at the time. It is hard to not draw comparisons, with Frampton following down an almost identical path. He too has even married a Catholic woman despite being Protestant, and he too has a large following of die-hard fans from both Catholic and Protestant backgrounds who attend his fights in large numbers.