Mugabe, who was declared a "national hero," ruled Zimbabwe for almost three decades and was battling ill health since his humiliating fall from office in November 2017.
Robert Mugabe, who led Zimbabwe with an iron fist from 1980 to 2017, has died aged 95, the country's president announced on Friday.
First heralded as a liberator who rid the former British colony of Rhodesia of white minority rule, Mugabe used repression and fear to hold on to power in Zimbabwe until he was finally ousted by his previously loyal military generals.
"It is with the utmost sadness that I announce the passing on of Zimbabwe's founding father and former President Robert Mugabe," Emmerson Mnangagwa said in a tweet.
"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."
Zimbabwe's president also declared Mugabe a "national hero," adding that the country would mourn the former leader until his burial.
"(Ruling party) ZANU-PF has met and accorded him the national hero status that he richly deserved," Mnangagwa said during an address to the nation aired on television.
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 (2/2)— President of Zimbabwe (@edmnangagwa) September 6, 2019
Mugabe had been battling ill health and his stamina seeped away rapidly following his humiliating fall from office in November 2017. He was hospitalised in Singapore for months for an undisclosed ailment, Mnangagwa had confirmed earlier this year.
No further details were immediately available about the circumstances of his death or where he died.
The Mugabe years are widely remembered for his crushing of political dissent and policies that ruined the economy.
The former political prisoner-turned-guerrilla leader swept to power in the 1980 elections after a growing insurgency and economic sanctions forced the Rhodesian government to the negotiating table.
In office, he initially won international plaudits for his declared policy of racial reconciliation and for extending improved education and health services to the black majority.
Human rights violations?
But that faded as rapidly as he cracked down on opponents, including a campaign known as Gukurahundi, in which an estimated 20,000 dissidents were killed.
The violent seizure of white-owned farms turned Mugabe into an international pariah – though his status as a liberation hero still resonates strongly in most of Africa.
Aimed largely at placating angry war veterans who threatened to destabilise his rule, the land reform policy wrecked the crucial agricultural sector, caused foreign investors to flee and helped plunge the country into economic misery.
Over the years, the Mugabe regime was widely accused of human rights violations and of rigging elections.
The topic of his succession was virtually taboo during Mugabe's decades-long rule and a vicious struggle to take over after his death became clear among the ruling elite as he reached his 90s and became visibly frail.
Reaction to Mugabe's death
Nigerian President Muhammadu Buhari, hailing him as the "founding father" of a nation, said Mugabe "fought for the independence of the country from colonial rule, and lived most of his life in public service."
Namibia's President Hage Geingob hailed him as a "warrior."
Geingob said: "Comrade Robert Mugabe (was) an outstanding revolutionary, a tenacious freedom fighter and dedicated Pan Africanist... President Mugabe made enormous sacrifices in the struggle against injustice and the liberation of Southern Africa from racist subjugation and colonial oppression."
"Mugabe was an outstanding national liberation movement leader and politician of Zimbabwe," said Chinese foreign ministry spokesman Geng Shuang.
"Throughout his life, he has firmly defended the sovereignty of his country, opposed foreign interference, and actively promoted China-Zimbabwe and China-Africa friendship and cooperation," Shuang.
Tanzania's President John Magufuli tweeted in Swahili: "Africa loses a brave, determined leader, an Africanist who turned the rejection of colonisation into action. May God let his soul rest in peace."
Russian President Vladimir Putin said: "Many important dates in Zimbabwe's modern history are tied to the name of Robert Mugabe. He made a great personal contribution to the battle for your country's independence, to the building of Zimbabwean state institutions."
South Africa's President Cyril Ramaphosa recalled two country's shared history and solidarity in fighting colonialism.
"Under President Mugabe’s leadership, Zimbabwe’s sustained and valiant struggle against colonialism inspired our own struggle against apartheid and built in us the hope that one day South Africa too would be free."
However, a statement from Briain's foreign ministry highlighted the human rights violations under Mugabe's rule.
"We express our condolences to those who mourn Robert Mugabe's death. However, Zimbabweans suffered for too long as a result of Mugabe's autocratic role," the statement said.
Europen Union's statement focused on the country's democracy.
"The EU will continue to stand by Zimbabwe and its people, to support reconciliation and to help ensure a united, prosperous, secure a democratic future for all Zimbabweans," a statement said.