Lee was born in Bow, London, England, to Irish Traveller parents. In 1998, his parents returned to Castleconnell, County Limerick in Ireland with their six children. Lee had previously been training at the Repton Boxing Club in London from the age of eight, and upon his family's return to Ireland, Lee and his brothers joined St Francis ABC in Limerick, where his boxing career took off.
Lee signed his first professional contract with Manny Steward in 2005. He then moved to Detroit, Michigan where he lived with his longtime manager and trainer until Steward died in 2012. Following his death, Lee moved to London where he joined up with English trainer Adam Booth It was with Booth that Lee won the WBO belt in 2014, becoming the first Irish boxer to win a world title on American soil since 1934. Lee is also the first member of the Irish Traveller community or any Traveller community to win a world title.
Lee represented Ireland at the 2002 World Junior championships in Santiago de Cuba, competing in the middleweight category. Lee fought five times in a week beating Ismail Sillakh and United States favourite Jesus Gonzales but lost the final to Cuban boxer Noelvis Diaz to claim the silver medal.
At the World Amateur Championships in Bangkok, Lee was beaten on points by eventual winner Gennady Golovkin who also defeated Lucian Bute and Matt Korobov on his way to the gold medal.
Lee traveled to Pula, Croatia for the European Amateur Championships in February 2004. He earned a bronze medal in the competition, and thereby qualified for the 2004 Summer Olympics at just nineteen years of age.
In June 2004, Lee won silver at the EU Amateur Championships. He lost to the vastly experienced, former world champion, Marian Simion in the Middleweight final.
Lee's first fight of the 2004 Olympics was against Mexican boxer Alfredo Angulo, who Lee defeated 38:23 on points. In the second round, Lee faced Hassan N'Dam N'Jikam of Cameroon. After four rounds the fight was drawn 27:27 and the bout was decided by "count-back". The verdict went the way of the Cameroonian, which ended Lee's hopes of a medal. Lee was bitterly disappointed in the result and stated "I just didn’t fight to my ability. But when I got back home the people treated me like I’d won the gold medal."
In February 2003, aged seventeen, Lee fought for the Irish senior amateur title in the middleweight division. That year he beat Eamonn O'Kane.(http://amateur-boxing.strefa.pl/Nationalchamps/Ireland2003.html) The following year, Lee won the title after overcoming Patrick Murray for the honour. In 2005 Lee retained the title, this time by defeating Eamonn O'Kane in the final.
After the Olympics, the Irish Sports Council had stated that they were prepared to fund Lee in order for him to continue at amateur level and compete at the Beijing Olympics. Lee however turned this offer down and signed a professional contract with trainer-manager Emanuel Steward, who had followed Lee's progress since the World Junior Championships. Lee subsequently emigrated to the United States where he trained at Steward's world-renowned Kronk Gym in Detroit. Lee made an immediate impression, with Steward recalling - "The first time he’d flown from Ireland to Chicago, then to Detroit, and he wanted to spar. I said ‘No, you must have jet lag.’ But he insisted, so I put him in with Cornelius Bundrage, who was then undefeated. Andy pulled a mouthpiece out of his pocket, borrowed boots from one guy and gloves from another, then he doggone whooped ‘K-9’s ass." His first professional bout was in March 2006, at the Joe Louis Arena, Detroit, in which Lee beat Anthony Cannon on a points decision over six rounds on a card that featured Johnathon Banks.
On 15 December 2007, Lee became the Irish Super-middleweight champion after he beat fellow Irishman Jason McKay at the National Stadium in Dublin.
In April 2007, HBO featured Lee as one of boxing's top prospects, with Larry Merchant commenting - "he looks like 10 million dollars". Star coach Steward was also quick to praise Lee, claiming on RTÉ television that by the end of 2008 he would defeat the then current world champion, Kelly Pavlik.
In December 2007, ESPN also listed Lee as a top prospect saying - "Lee has all the potential to be the next great middleweight star. The 2004 Irish Olympian is a 6 foot 2 inch southpaw with skills, power and a streak as mean in the ring as he is personable outside of it. With trainer/manager Emanuel Steward molding him, Lee is moving quickly. He was 8-0 in 2007, including a thunderous knockout of faded former titleholder Carl Daniels. Lee is as blue chip as they come. If you could get stock in a prospect, he'd be near the top of the buy list."
On 21 March 2008, during his debut on ESPN 2, Lee suffered his first defeat after losing by TKO in the seventh round to Brian Vera. The stoppage was mildly controversial, as Lee was winning on points, and was still punching back as the referee Tony Chiarantano stepped in. However, he had been reeling and unsteady from heavy punishment and fatigue for several minutes, and neither he nor his corner complained at the stoppage.
On 19 July 2008 Lee defeated Willie Gibbs in the last round, when Gibbs's corner threw in the towel after a barrage of shots from Lee with 7 seconds to go.
On 21 March 2009, appearing on the undercard of the Bernard Dunne world title fight against Ricardo Cordoba, Lee beat the tough German brawler Alexander Sipos in a unanimous decision. This was a reckoning of sorts, as it occurred on the one year-to-the-day anniversary of Lee's first and only professional defeat.
On 20 June 2009, Lee outpointed Olegs Fedotovs in front of 60,000+ at the Veltins Arena in Gelsenkirchen, Germany for his 18th victory as part of the Klitschko-Chagaev undercard.
On 22 August 2009, Lee stopped Andy Shuler in the 8th round of a bout in Hammond, Indiana to earn his 19th victory and 14th KO.
A hometown crowd turned out in Limerick, 14 November 2009, to watch Lee defeat Frenchman Affif Belghecham in a ten-round battle of the southpaws. Shannonsider Lee outpointed the Frenchman 99–92; Lee stopped Mamadou Thiam the following year in the same venue.
On 30 July 2010 Lee faced James Cook in Miami, Oklahoma and won the bout by a fifth-round knockout.
On 12 March 2011, Lee fought Craig McEwan at Foxwoods Resort Casino in Mashantucket, Connecticut, and won via technical knockout at 0:56 in the 10th round.
He avenged his loss to Brian Vera on 1 October 2011 by unanimous decision.
On 10 March 2012, Lee Knocked out Mexico's Saul Duran in the 2nd round of a stay busy fight.
On 16 June 2012, Lee challenged undefeated Titleholder Julio Cesar Chavez Jr. for the WBC World Middleweight Title in the Sun Bowl Stadium in El Paso, Texas televised on HBO World Championship Boxing. Lee got off to a good start, using his jab and effectively outboxing Chavez Jr. in the center of the small 16 foot ring, however, Chavez Jr. eventually got through using his substantial weight advantage, and with his stronger physicality, essentially turning the fight in his favor. Near the middle rounds, Lee began to lose stamina due to Chavez Jr's focus on body work. In round 7, referee Laurence Cole stopped the bout with Lee still on his feet after Chavez Jr. stunned him. Lee subsequently took a barrage from Chavez Jr. on the ropes leading to the stoppage. Lee was up on all the official judges cards at the time.
Under the tutelage of new trainer Adam Booth, Lee returned to winning ways, after his loss to Chavez Jr., by outpointing former Irish super middleweight champion Anthony "The Pride" Fitzgerald (13–3, 4 KO's) over ten rounds in a middleweight fight held at the Odyssey Arena in Belfast on 9 February 2013 on the undercard of a Carl Frampton Vs Kiko Martinez EBU (European) super bantamweight title fight.
On 7 June 2014, in Madison Square Garden, on the undercard of the Pay-Per-View fight between Miguel Cotto and Sergio Martinez, Andy Lee met hard-hitting Virgin Islander John Jackson in a 154-lb bout. John Jackson is the son of the great light-middleweight puncher Julian Jackson. In the first round Lee was knocked down for the first time in his amateur or pro career respectively on a hard right-hand counter by the heavy-handed Jackson. Lee regained his composure but proceeded to lose the next 3 rounds in a row, he spent the majority of the time tactically looking to catch Jackson coming in with a right hook counter. In round 5 Jackson unleashed a furious flurry of punches and trapped Lee on the ropes, Lee moved off the ropes, but as Jackson moved in to close the show, Andy Lee caught him with the perfectly timed right hook counter that he was looking for and knocked Jackson completely out.
After the comeback knockout victory over John Jackson, Andy Lee secured himself a 13 December WBO World Middleweight Title shot against the then undefeated former 2008 Russian Olympian, Matt Korobov. This was to be on the HBO triple-header that featured the fight between Timothy Bradley and Diego Chaves as its main event. In front of a sold out crowd at the Cosmopolitan of Las Vegas, Lee and Korobov fought a closely contested chess match before Lee wobbled Korobov with a straight left in the 3rd round. However Korobov regained control and seemed to be controlling the pace of the fight until round 6, when Lee connected on a right hook in an exchange and badly hurt Korobov, a flurry of 18 straight unanswered punches forced referee Kenny Bayless to stop the contest handing Lee the 6th-round TKO victory and the WBO World Middleweight Title. With this most impressive win, Lee became the first Irishman from Ireland (obviously there were plenty of real Irish blooded Americans, Irish from England, Australia, etc.) to win a world title on American soil since 1934.
After stating that he wanted to fight the best in the world, Lee postponed a title defense in Ireland to defend his WBO Title against former WBO World Champion, unbeaten Peter Quillin in the Barclays Center on 11 April. Quillin failed to make weight at the weigh-in for the bout however, meaning regardless of the result of the fight, he was ineligible to win Lee's WBO Middleweight World Title. This fight took place as part of a Premier Boxing Champions show on NBC and was on a card that included Danny García fighting Lamont Peterson in the main event. The fight began with what appeared to be a fairly good first round for Lee until with 30 seconds left, Lee was dropped hard, and hurt by an overhand right delivered by Quillin. Lee survived the round, but two rounds later in round 3, found himself on the canvas again, albeit this time in controversial fashion, as it was discovered that Lee went down mostly due to Peter Quillin stepping on his foot. As the fight wore on the rounds seemed to be close and went back and forth, in the seventh round, Lee landed a hard left hand followed by a clean right hook to Quillin's chin which sent him sprawling to the canvas, evening the fight up on the cards and handing Peter Quillin the first knockdown of his career. The fight continued to go back-and-forth and by the end of the 12th round, official judges scores were 113-112 for Lee, 113-112 for Quillin, and 113-113 even, rendering the official outcome of the bout a split draw.
It was announced that on 19 September 2015, Andy Lee would defend his WBO Middleweight title against unbeaten Billy Joe Saunders in his home city of Limerick, Ireland. However the bout was rescheduled for 19 December, and instead took place in the Manchester Arena. Due to a slow start by Lee, Saunders was able to score 2 knockdowns. However, once again, Lee came on strong in the second half of the fight, outboxing Saunders for stages. However, Lee's late rally was not enough to close the gap of the early lead Saunders gained. With scores of 115-111, 114-112, and one judge scoring it a draw at 113-113, Lee lost a close majority decision on the scorecards.