Sergio Aguero says he is "proud" of his career after accepting the "very difficult" reality of retiring from the sport to protect his health.
The 33-year-old sobbed while announcing the news on Wednesday, fewer than six months after joining Barcelona.
The former Manchester City striker was taken to hospital on 30 October after experiencing "chest discomfort" during a 1-1 draw with Alaves.
"The decision I have made, I have taken it for my health," said Aguero.
Manchester City manager Pep Guardiola was among a small crowd watching Aguero make the announcement next to the Nou Camp pitch.
Aguero, who ends his career with 427 goals in 786 games, took time to compose himself after crying at the start of the event and added: "This conference is to communicate that I have decided to stop playing football. It's a very difficult moment.
"When they did the first physical test on me in the clinic, the medical staff called me to tell me there was a very big possibility that I wouldn't be able to keep playing. From that point I was processing it all but it wasn't easy. One of the doctors told me straight up, 'that's enough'.
"I want to tell everyone that I did everything possible. I dreamt about playing football since I was five years old and I first touched a ball. I never thought I would get to Europe, so I want to show my gratitude to everyone regardless of where I trained.
"I'm proud of the career I've had and am fortunate it is happening to me now rather than before. I don't know what awaits me in the next life but I know there are a lot of people who love me and want the best for me."
Aguero's incredible stats
Aguero is the fourth-highest scoring player in Premier League history with 184 goals in 275 games, behind only Alan Shearer (260), Wayne Rooney (208) and Andrew Cole (187). He is also the league's highest-scoring overseas player, having registered nine more goals than Thierry Henry (175).Aguero scored every 108 minutes in the Premier League, comfortably the best rate in the competition's history. Indeed, he could play another 2,520 minutes (28 games) of Premier League football without scoring and would still have the best minutes-per-goal ratio of any top-flight player with more than 20 goals.The Argentine scored 18 hat-tricks in his career, including 12 in the Premier League - a record in England's top flight.He scored 20+ goals in all competitions in 12 of 13 campaigns between 2007/08 and 2019/20, reaching 30 or more on five separate occasions during his time at Manchester City.Aguero scored 36 goals for Manchester City in the Champions League, the joint-highest total a player has registered for an English side in the competition's history (along with former Chelsea striker Didier Drogba).He found the net against 128 different opponents, including the likes of Barcelona, Real Madrid, Bayern Munich, Chelsea, Liverpool and Manchester United.There were 16 years and 332 days between Aguero's first career goal in November 2004 (for Independiente) and his final strike for Barcelona - against Real Madrid in October 2021.A Premier League legend
Despite an untimely end to his spell at Barcelona, there can be no doubting Aguero's status as one of the foremost strikers of the 21st Century.
After starting out with Independiente in Argentina he moved to Atletico Madrid, winning the Europa League in 2010 and scoring 101 goals in 234 appearances.
That record attracted the interest of an upwardly mobile Manchester City, who paid a reported £38m to bring him to Etihad Stadium.
He would go on to become a club and Premier League legend during a 10-year spell in England, winning five Premier League titles, one FA Cup and six League Cups.
"Atletico Madrid took a bet on me at 18 years old, that I could do things well in Europe," Aguero said at his news conference. "People at Manchester City, you all know how I feel. They look after me really well.
"When a player plays, they always want to keep winning more things, but I think I can be happy with the titles I won. Anyone can always do a bit more, but I think I did my best for me and my clubs."
Aguero left City in the summer having broken their all-time scoring record, with 260 goals in 390 games, including 16 hat-tricks.
The Argentine is also responsible for arguably the Premier League's most iconic moment, scoring with virtually the last kick of the 2011-12 season to seal a victory over Queens Park Rangers that earned Manchester City a first top-flight title since 1968 and denied fierce rivals Manchester United by virtue of goal difference.
A sad end with Barcelona
Aguero's great friendship with compatriot Lionel Messi meant a move to Barcelona was an attractive one after it became clear he would be allowed to leave Manchester City.
He had won over City boss Pep Guardiola, who initially had concerns about the striker's ability to fit into his style of play, but injuries limited Aguero's playing time during his final season at the Etihad.
But the switch to Barcelona went badly from the start. The club's financial problems meant there were problems registering their new signings, including Aguero.
And those same issues led to the departure of Messi to Paris St-Germain.
When Aguero was eventually registered, he suffered a calf injury that kept him out until October and he only made five appearances for the club in all.
He scored a 90th-minute consolation in his only El Clasico appearance against Real Madrid, on 24 October, and three days later made his first start for the club.
But his withdrawal against Alaves in October was followed by a "cardiac exam" and Aguero said on social media he would follow doctors' advice in making a decision about his playing future.
He said he would take 90 days to assess his progress, with reports suggesting he had been diagnosed with cardiac arrhythmia - an irregular heartbeatexternal-link.
But his decision has come sooner than expected.
His final contribution for Argentina came at the summer's Copa America, a substitute appearance in the quarter-final victory over Ecuador as La Albiceleste went on to win the trophy for the first time in 28 years.
Analysis - 'Unfinished business in Argentina but a magnificent legacy'
South American football expert Tim Vickery
There were still a couple of things to cross off on Aguero's list of things to do. One was to round off his career where it all started, at Independiente in Argentina.
When Independiente sold him to Atletico Madrid, they entirely rebuilt the stadium on the proceeds and it was always a dream of Aguero himself and of the club's fans that he would one day come back and play in the house he built
So scratch that one, it seems. The other one is another World Cup with Argentina because there are a couple of little holes in a fabulous career. One is the Champions League and the other is a great tournament. He did win the Copa America in the middle of the year, but he was a reserve, he hardly got on the field in the knockout stages and he didn't score.
Although he scored 42 goals for Argentina, and only two men have scored more - Gabriel Batistuta and Lionel Messi - he never truly had a great tournament and quite often come the end-of-season tournaments he was dragging his weary carcass around the field.
Maybe it is a shame Pep Guardiola didn't get his hands on him earlier because the best tournament he played was the last World Cup in Russia, where Argentina were otherwise an absolute shambles.
Now they are the best team they have been since he started playing for them, it would have been lovely for him to have one last go at the World Cup in a year's time.
It is not a moment of his choosing but what a legacy he has left and what a magnificent player he was.