Kasparov, 41, became the youngest world champion ever at 22 and was known for an aggressive style that shunned settling for a draw. He was retiring in part because he saw no real goals left in chess, he said.
The announcement by the Russian grandmaster - the world's No 1 ranked chess player since 1984 - came shortly after he won the 14-match Linares tournament in Spain yesterday.
"Before this tournament I made a conscious decision that Linares 2005 will be my last professional [tournament], and today I played my last professional game," Kasparov said at a news conference last night.
He said his last games were "very difficult for me to play under such pressure, because I knew it was the end of the career which I could be proud of".
Kasparov has expressed increasing exasperation over the professional chess world, which has been bitterly divided since 1993 into two rival federations, with rival champions. He reiterated yesterday that he was disappointed that a campaign to reunify the title had failed.
He said he would continue to play chess, write books about it and take part in tournaments, such as so-called knockout events, in which he plays many opponents at once, or in speed-chess games. But he is saying goodbye to lucrative, top-level professional play.
Kasparov could be planning to concentrate on his participation in Russian politics. He has emerged as an outspoken critic of the Russian president, Vladimir Putin, and is playing a leading role in a group formed by prominent liberal opposition leaders called Committee 2008: Free Choice.
Born in Baku in the then-Soviet republic of Azerbaijan, Kasparov will be remembered in part for one of his few losses, a 1997 match against the IBM supercomputer Deep Blue that was seen by some as a watershed moment in technological advancement.
In 2003, Kasparov averted a similar defeat when he agreed to a draw in the last game of his series against Deep Junior, which could process 3m chess moves a second. The six-game series, dubbed Man v Machine, tied 3-3.
Shay Bushinsky, one of two Israeli programmers of Deep Junior, said Kasparov's resignation had been "on the cards".
Mr Bushinsky said the chess champion told him, in a meeting last month, that he had been frustrated for a number of years because there was no real world championship in which he could compete. Mr Bushinsky told the Associated Press that, as a chess player, Kasparov was "the closest thing to a computer that I know as a man. Sometimes I think he has silicon running in his veins."
"Kasparov has the most incredible look-ahead and memory capabilities I have ever seen," he said.
Kasparov's chess talent was apparent at an early age. He started attending the Botvinnik chess school in 1973, when he was 10. Two years later, he became the youngest ever player to win the USSR junior championship. At 16 he won the world junior championship and achieved the title of grandmaster on his 17th birthday.
His first title match, from September 1984 to February 1985, against Anatoly Karpov, was the longest in chess history. After 48 games, the psychological and physical strain on Karpov, who was leading but appeared likely to lose, caused chess authorities to end the match inconclusively. Kasparov won a rematch six months later, becoming the youngest world champion ever. He defended his title against Karpov in 1986, 1987 and 1990.
GM Garry Kasparov
In the hands of this young man lies the future of chess. – Mikhail Botvinnik (on Kasparov in the late Seventies)
It was the beauty and brilliance of tactical blows that captivated me in early childhood. – Garry Kasparov
My chess philosophy has largely been developed under the influence of Ex-World Champion Mikhail Moiseevich Botvinnik. I am sure that the five years I spent at Botvinnik's school (1973-1978) played a decisive role in my formation as a chess player and determined the path of my subsequent improvement. – Garry Kasparov
I singled out for me a group of chess players from whom I wanted to borrow the best qualities: the psychological stability from Karpov, the meticulous positional technique from Petrosian, the logic from Botvinnik, the intuition from Alekhine, the ability of taking a risk from Tal. – Garry Kasparov
Alexander Alekhine is the first luminary among the others who are still having the greatest influence on me. I like his universality, his approach to the game, his chess ideas. I am sure that the future belongs to "Alekhine" chess. – Garry Kasparov
I try to play, always, beautiful games…always I wanted to create masterpieces. – Garry Kasparov
I want to win, I want to beat everyone, but I want to do it in style! – Garry Kasparov
Chess for me is art. – Garry Kasparov
Chess is mental torture. - Garry Kasparov
My play is based on the most general laws of chess and the particular features of the position. – Garry Kasparov
The point about concentration is that it is the only way to find something new and unusual at the chessboard; the only way to create surprise with fresh ideas. – Garry Kasparov
We like to think. – Gary Kasparov (on why he and Karpov get into time trouble so often)
In conclusion, if you want to unravel the multitude of secrets of chess then don't begrudge the time. - Garry Kasparov
My nature is that I have to excite myself with a big challenge. - Garry Kasparov
Kasparov feels Indian positions with his fingertips, but did not risk playing the KID against Karpov until their 4th match. And when Garry did not lose, he confirmed his absolute dominance over Karpov. It became clear that Karpov's attempts to regain the title would never succeed. - Alexsander Shashin
To make a rather primitive classification, the average grandmaster knows about 1,500 - 2,000 typical positions, including the opening, possible middlegame plans, and some outlines of endgame. Super GMs, like Kramnik or Anand, have a wider and deeper knowledge. As for Kasparov, his knowledge is truly head-spinning, I guess, his number of positions might exceed 10,000. Garry's memory is phenomenal! I think it even impedes him during the game. - Valeri Tsaturian
Potentially, Garry is an outstanding tactician who thinks originally and has a fine, sharp sense for dynamic positions. The trainers who worked with him concentrated on another of his assets, the most obvious one being his unique memory. This natural gift and his strong character, multiplied by his tremendous working ability, along with his ability to accumulate and retain information, produced the world champion; perhaps the greatest chess player of all time. Nevertheless, I believe that Garry did not realize his true chess potential to the maximum. Great knowledge is a great burden. Young Kasparov was incredibly inventive, even in difficult positions. He knew how to transform them, to explode the situation on the board in his favor, and he collected points from the strongest opponents, who could not cope with such complications. Garry's chess talent had a lot in common with Tal's. Later these traits were greatly developed. Garry has been the world's strongest player for 20 years and still he is not fully satisfied. Due to the constant pressure on him, Garry can't play a single game for his own pleasure. Those who've seen friendly games by Kasparov, when he plays in a relaxed manner without worrying about the outcome, will never forget it: what spectacular chess! - Valeri Tsaturian
An aggressively inscrutable player, Kasparov strives to gain deep positional sacrifices: Even when he can't calculate the end result conclusively, he can make sophisticated generalizations. He does anything to get the initiative and to force the play. Inevitably, he emerges from a forest of complications - in which his intentions aren't all that clear - with the advantage. He's not as artful or as clear as Fischer, but his play coincides with the realities of the day, which are all about defense. Clarity of style no longer makes sense. Great players hide their intentions. – Bruce Pandolfini
Kasparov always seems to find some sparks to create a fire on the board. – Lubomir Kavalek
Typical Kasparov. Instead of simplifying to stagnant equality, he seeks counter chances on the kingside. Forever confident. That's why he's the best in the world! – Yasser Seirawan (commenting on a Kasparov game)
When your house is on fire, you can't be bothered with the neighbors. Or, as we say in Chess, if your King is under attack you don't worry about losing a Pawn on the Queen's side. - Gary Kasparov
Sometimes Kasparov does things that no other chessplayer is able to do, things that are so stunning that colleagues and spectators ask themselves in astounded admiration how for heaven's sake it is possible that a human being can invent them. – Hans Ree
Look at Garry Kasparov. After he loses, invariably he wins the next game. He just kills the next guy. That's something that we have to learn to be able to do. - Maurice Ashley
If there is one single facet of chess in which Garry has well and truly dominated his opposition it is in the opening phase of the game. The breadth of his opening preparation is as vast as it is deep, ensnaring practically every chess grandmaster he has ever faced. I've witnessed some of the world's very best grandmasters shaking their heads, staring at a lost position shortly after breaking beyond the opening stages. – Yasser Seirawan
Considering the youth of many of today's chess fans it might be better to reminisce about how terrifying Kasparov was in the 80s, but no time for ancient history today. Nobody gets a name like "Beast" after they're 35. – Mig Greengard
He has been known by many names: the Prince of Darkness, the Boss, the Great One, Gazza, the Beast, and the Dark One. I think he enjoys all of this very much. – Kelly Atkins
Garry Kasparov, the man who throws rocks as if they are tennis balls, uproots heavy trees with bare hands and eats strong international masters for breakfast. – Hans Ree
Kasparov definitely has a great talent. There is nothing in chess he has been unable to deal with. The other world champions had something 'missing'. I can't say the same about Kasparov: he can do everything. If he wishes to play some type of positions brilliantly, he will do it. Nothing is impossible for him in chess. - Vladimir KramnikKasparov is the greatest player in the history of chess. I am a big fan of Capablanca, but Kasparov is the greatest. - Alexsander Shashin