The country's incumbent President Emmerson Mnangagwa, who took over from Mugabe after the military seized control of the country in 2017, tweeted news of the latter's death.
"It is with the utmost sadness that I announce the passing on of Zimbabwe's founding father and former President, Cde Robert Mugabe," Mnangagwa said.
The nonagenarian leader, who ruled the Southern African country for nearly four decades until being ousted, had been receiving treatment in Singapore since April due to prolonged illness.
"Cde Mugabe was an icon of liberation, a pan-Africanist who dedicated his life to the emancipation and empowerment of his people. His contribution to the history of our nation and continent will never be forgotten. May his soul rest in eternal peace," Mnangagwa added.
Mugabe was born on February 21, 1924. He began his political career as a leader in the quest for the independence of Zimbabwe then known as Rhodesia and was regularly compared to South Africa's venerated freedom fighter Nelson Mandela.
As a revolutionary guerrilla leader, he fought white minority rule and spent years in jail as a political prisoner.
In the mid-70s, he assumed leadership of the political wing of the Zimbabwe African National Union (ZANU-PF), a militant liberation movement based in Mozambique.
From there, he helped orchestrate an armed resistance against white rule, emerging as a war hero both at home and abroad when the conflict ended in 1979.
He became the first Prime Minister of independent Zimbabwe after elections in February 1980. But the descent into tyranny didn't take long as he abolished the office in 1987 and became President.
Mugabe's early years were praised for broadening access to health and education for the black majority.
Later, his hardline policies drove the country's flourishing economy to disintegrate after a programme of land seizures from white farmers, and agricultural output plummeted and inflation soared.
Mugabe presided over forces that carried out a string of massacres in opposition strongholds, and the country's Fifth Brigade is believed to have killed up to 20,000 people, mostly supporters of his main political rivals.
As the country was plunged into economic ruin, Mugabe and his wife Grace faced fierce criticism for leading lavish lifestyles.
Mugabe who infamously had claimed that "only God" could ever remove him from office was deposed in the 2017 coup when members of his own party turned against him after he dismissed his longtime ally, then-Vice President Mnangagwa, to make way for his much younger wife.
The African National Congress said it "mourns the passing of friend, statesman & revolutionary comrade Robert Mugabe".
Nelson Chamisa, leader of the country's main opposition party, the Movement for Democratic Change, said that it was a "dark moment for the family because a giant among them has fallen".
The US Embassy in Harare has tweeted their condolences to Mugabe's family and to the people of Zimbabwe, focusing on Mugabe's "legacy in securing" the country's independence.
South Africa's President Cyril Ramaphosa called Mugabe a "champion of Africa's cause against colonialism" who inspired our own struggle against apartheid".
Kenya's President Uhuru Kenyatta called Mugabe "a man of courage who was never afraid to fight for what he believed in even when it was not popular".
UK Labour peer Peter Hain, a former Africa Minister and anti-apartheid campaigner, called Mugabe "a tragic case study of a liberation hero who then betrayed every one of the values of the freedom struggle".
( With inputs from IANS )