His death comes just months after Mr McGuinness stood down in January in protest at the Democratic Unionst Party’s (DUP) handling of the “cash for ash” energy scandal, triggering a snap election.
His retirement came amid health concerns, but he, his family and colleagues did not specify the nature of his illness.
Responding to the news, Sinn Fein said in a statement: “It is with deep regret and sadness that we have learnt of the death of our friend and comrade Martin McGuinness who passed away in Derry during the night.
“He will be sorely missed by all who knew him.”
Hundreds of people lined the streets of Londonderry on Tuesday as Mr McGuinness’s coffin, draped in the Irish flag, was carried past.
Sinn Fein president Gerry Adams and the party’s leader at Stormont, Michelle O’Neill, draped the flag over his coffin in Derry’s William Street and crowds applauded as he was borne through the streets of his native city – where the Northern Ireland conflict began in 1969 and ended 30 years later.
The former Deputy First Minister’s wife Bernie bore him past the Free Derry Corner before his two sons, Fiachra and Emmett, shouldered his remains into his house.
After hearing of his death, Sinn Fein president Gerry Adams paid tribute to his lifelong friend, saying: “Throughout his life Martin showed great determination, dignity and humility and it was no different during his short illness.
“He was a passionate republican who worked tirelessly for peace and reconciliation and for the reunification of his country.
“But above all he loved his family and the people of Derry and he was immensely proud of both.”
During his time in office Mr McGuinness forged an unlikely friendship with the then DUP leader Ian Paisley and the two earned the nickname the Chuckle Brothers.
1/2 Very sorry to hear about the passing of Martin McGuinness.Look back with pleasure on the remarkable year he and my father...— Kyle Paisley (@JCKP1966) March 21, 2017
2/2 spent in office together and the great good they did together. Will never forget his ongoing care for my father in his ill health.— Kyle Paisley (@JCKP1966) March 21, 2017
A Twitter account in the name of Mr Paisley’s son Kyle said: “Very sorry to hear about the passing of Martin McGuinness. Look back with pleasure on the remarkable year he and my father spent in office together and the great good they did together.
“Will never forget his ongoing care for my father in his ill health.”
Prime Minister Theresa May said: “While I can never condone the path he took in the earlier part of his life, Martin McGuinness ultimately played a defining role in leading the republican movement away from violence. In doing so, he made an essential and historic contribution to the extraordinary journey of Northern Ireland from conflict to peace.
“While we certainly didn’t always see eye to eye even in later years, as Deputy First Minister for nearly a decade he was one of the pioneers of implementing cross community power sharing in Northern Ireland. He understood both its fragility and its precious significance and played a vital part in helping to find a way through many difficult moments.
“At the heart of it all was his profound optimism for the future of Northern Ireland – and I believe we should all hold fast to that optimism today.”
Martin McGuinness played a huge role in bringing about peace in Northern Ireland. He was a great family man and my thoughts are with them— Jeremy Corbyn MP (@jeremycorbyn) March 21, 2017
Labour leader Jeremy Corbyn said on Twitter: “Martin McGuinness played a huge role in bringing about peace in Northern Ireland. He was a great family man and my thoughts are with them.”
So sad Martin McGuinness has died. Some will never forgive his past but without him there would be no peace. The man I knew was a great guy— Alastair Campbell (@campbellclaret) March 21, 2017
Mr McGuinness was described as a “great guy” by former Labour communications chief Alastair Campbell.
He tweeted: “So sad Martin McGuinness has died. Some will never forgive his past but without him there would be no peace. The man I knew was a great guy.”
President of Ireland Michael D Higgins led tributes from the Republic, saying Mr McGuinness’s death leaves a gap that will be hard to fill.
“The world of politics and the people across this island will miss the leadership he gave, shown most clearly during the difficult times of the peace process, and his commitment to the values of genuine democracy that he demonstrated in the development of the institutions in Northern Ireland,” he said.
Mr Higgins said Mr McGuinness made an immense contribution to peace and reconciliation in Northern Ireland.
But former Tory Cabinet minister Lord Tebbitt denounced Mr McGuinness as “a coward who never atoned for his crimes”.
The peer, whose wife Margaret was paralysed when the IRA bombed a Brighton hotel during the 1984 Conservative Party conference, said the world is a “sweeter and cleaner” place now the former Deputy First Minister is dead.
Former Prime Minister Tony Blair said: “I grew up watching and hearing about the Martin McGuinness who was a leading member of the IRA engaged in armed struggle. I came to know the Martin McGuinness who set aside that armed struggle in favour of making peace.
“There will be some who cannot forget the bitter legacy of the war. And for those who lost loved ones in it that is completely understandable.
“But for those of us able finally to bring about the Northern Ireland peace agreement, we know we could never have done it without Martin’s leadership, courage and quiet insistence that the past should not define the future.”
He added: “Whatever the past, the Martin I knew was a thoughtful, reflective and committed individual. Once he became the peace maker he became it wholeheartedly and with no shortage of determined opposition to those who wanted to carry on the war.”
My heart is broke this morning. We have lost a legend, a giant of a man. I’m very proud to say he was my friend and mentor x— michelle oneill (@moneillsf) March 21, 2017
Mr McGuinness’s successor as the party’s leader at Stormont, Michelle O’Neill, paid tribute.
She tweeted: “My heart is broke this morning. We have lost a legend, a giant of a man. I’m very proud to say he was my friend and mentor x.”
Irish Taoiseach Enda Kenny said: “I was deeply saddened to hear of the death of Martin McGuinness today. His passing represents a significant loss, not only to politics in Northern Ireland but to the wider political landscape on this island and beyond.
“Martin will always be remembered for the remarkable political journey that he undertook in his lifetime. Not only did Martin come to believe that peace must prevail, he committed himself to working tirelessly to that end.
“Martin was one of the chief architects of the Good Friday Agreement and he worked resolutely in the years that followed it in pursuit of its full implementation. I got to know Martin well in recent years, including through our working together in the North South Ministerial Council.
“His commitment to securing enduring peace and prosperity for all of the people of Northern Ireland was unwavering throughout this time. He strove to make Northern Ireland a better place for everyone, regardless of background or tradition.”
Former Taoiseach Bertie Ahern, who was central to the Good Friday Agreement being signed, described Mr McGuinness as an extraordinary person, honest in his efforts and an upfront negotiator.
“In negotiations when there is a lot at stake and it can’t be a winner-takes-all, Martin understood compromise,” he told RTE Radio.
“He listened and he was able, I think, to arbitrate between different points of view.”
He added: “He moved from a very difficult past where he took a particular side and he was a good person to negotiate with and certainly I considered him as a good friend as we went through 25 years of discussions.”
SDLP leader Colum Eastwood said Mr McGuinness’s death is a “significant moment in the history of this island”. He described the journey of the former IRA man to the forefront of the political scene as “remarkable”.
Extending sympathy to Mr McGuinness’s wife and children, he said: “It is appropriate that we reflect on Martin’s remarkable journey, made possible by men and women from all traditions across this island who forged a peace process from the fire of a terrible conflict.
“History will record his political career as a journey – one born in a tradition of violence but, in a testament to Martin’s character, that arrived at his true calling in politics, people and the art of persuasion.
“Those who knew him will know that his warm and affable nature undoubtedly made it easier to reach beyond his own political base.”