Bernardo Provenzano had spent the past 42 years on the run.
For more than four decades, police hunted Provenzano relying only on a computer-generated picture compiled from photos from the 1950s.
They also had a description of his height (1.65 metres) and his weight (68 kilograms) plus the fact that he had a scar on his neck.
There had been reports that he had died but Provenzano, 73, was very much alive when he was picked up in his Sicilian heartland, Corleone near Palermo.
According to the Italian news agency Ansa he was arrested in an "isolated hut, near a sheepfold", was wearing jeans and a blue vest and "was thin with a hollow face".
He put up no resistance when an elite police unit arrested him and at once admitted his identity.
"Provenzano was not betrayed by anyone, we caught him thanks to inquiries carried out in the old way, by following and listening," said Palermo police chief Giuseppe Caruso.
By the time he arrived in Palermo in an armoured vehicle the white-haired boss of all the bosses was handcuffed, wearing a check shirt and a dark anorak.
Some of those waiting shouted abuse.
The arrest was the result "of discreet, patient, determined and professional work by the law enforcement authorities" which had "lasted several years", senior regional and local legal authorities said in a statement, without specifying when Provenzano was picked up.
He was born Corleone in January 1933 and became a "godfather" of the mob and capo of its chief decision-taking organisation.
"If he was a ghost, then we are ghost-catchers," exulted national anti-mafia prosecutor Pierro Grosso.
In 1958, at the age of 25, Provenzano was involved in the murder of a rival Corleone mafia leader, Michele Navarra.
He went in hiding in 1963 to escape an arrest warrant for the killing.
Provenzano became second in command to mafia leader Toto Riina, who presided over a series of gangland wars and killings of top judges, which were a hallmark of Italian life in the 1980s.
When Riina was arrested in 1993, and later jailed for life, Provenzano became the de facto head of the mafia, capo dei capi (boss of bosses), and Italy's most wanted man.
He gained the nicknames of "the tractor", due to his ruthless persistence, and "the accountant", because of his mastery of the organization's finances.
He was given three life sentences in absentia.
Provenzano was credited with devising a new, quieter strategy for the Mafia, relying less on murders and violence and more on infiltrating Sicilian society and luring institutions into lowering their guard.
He avoided capture on many occasions.
In 2003, according to the Italian authorities, he was twice treated in a Marseille hospital in southern France for a prostate condition, passing himself off as a Sicilian baker.
In January last year Grasso claimed to have "dismantled Provenzano's telecommunications ministry" and "cut all his channels, his information networks".
But, he conceded, "Provenzano is strong, very careful and we have to admit that."
On March 31 this year, a statement by his lawyer published in the Italian press even asserted that he had been "dead for years."
Anti-mafia prosecutors however dismissed the claim, and said they had evidence that he had undergone prostate surgery in a clinic in southern France in 2003, under the assumed identity of a baker.
Witnesses who had seen him there helped create an identikit picture, which the authorities released in March last year.