“The commander in chief of the Cuban revolution died late on Friday,” President Raul Castro said.
President Castro told the nation in an unexpected late night broadcast on state television that Fidel Castro had died and would be cremated later on Saturday.
There would now be several days of national mourning on the island.
Raul Castro ended the announcement by shouting the revolutionary slogan: “Towards victory, always!”
Barring the occasional newspaper column, Fidel Castro had essentially been retired from political life for some time.
The revolutionary icon, one of the world’s best-known and most controversial leaders, survived countless US assassination attempts and premature obituaries, but in the end proved mortal after suffering a long battle with illness.
Castro ruled Cuba as a one-party state for almost half a century before handing over the powers to his brother Raul in 2008.
His supporters praised him as a man who had given Cuba back to the people. But his opponents accused him of brutally suppressing opposition.
In April, Castro gave a rare speech on the final day of the country’s Communist Party congress.
He acknowledged his advanced age but said Cuban communist concepts were still valid and the Cuban people “will be victorious”.
“I’ll soon be 90,” the former president said, adding that this was “something I’d never imagined”.
“Soon I’ll be like all the others, to all our turn must come,” Fidel Castro said.
Born in 1926 in the south-eastern Oriente Province of Cuba, Castro was imprisoned in 1953 after leading an unsuccessful rising against Batista’s regime and was released in 1955 under an amnesty deal.
Castro was elected in 1976 as President by Cuba’s National Assembly, he reaches an agreement in 1992 with US over Cuban refugees.
In 2008 castro stands down as President of Cuba due to health issues.
An accomplished tactician on the battlefield, he and his small army of guerrillas overthrew the military leader Fulgencio Batista in 1959 to widespread popular support.
Within two years of taking power, he declared the revolution to be Marxist-Leninist in nature and allied the island nation firmly to the Soviet Union.
Yet, despite the constant threat of a US invasion as well as the long-standing economic embargo on the island, Castro managed to maintain a communist revolution in a nation just 90 miles off the coast of Florida.
Despised by his critics as much as he was revered by his followers, he outlasted ten US presidents and defied scores of attempts on his life by the CIA.