The President, Mrs McAleese, said: "It was with great sadness that I learned of the passing of the Queen Mother. She was a remarkable woman whose personality, fortitude and strength of character shone through in an extraordinary way to add to her long life.
"She had many admirers in Ireland who will mourn her passing. The Queen Mother will be sorely missed by her family and by the British nation and we offer them our sincerest sympathies," the President said.
The Taoiseach, Mr Ahern, in a message of condolence said: "The Queen Mother had a personal grace and charm which endeared her not only to the citizens of Britain but also to many people here in Ireland.
"She carried out her many duties and public appearances with a great sense of dignity combined with that friendliness and openness which had become her trademark.
"On my own behalf and on behalf of the Irish Government I offer my sympathies to the Royal family and to the people of Britain on their great loss," he said.
The Anglican Primate of Ireland, Archbishop Robin Eames, said: "The immense sadness that will be felt by so many people at home and abroad at this news will undoubtedly be reflected by members of the Church of Ireland as they recall a lady of great dignity, strong Christian principles and her devotion to family life," he said.
In a joint statement, the North's First Minister, Mr David Trimble, and the Deputy First Minister, Mr Mark Durkan, said: "From her first visit in 1924 as Duchess of York, she came to Northern Ireland often and due to the affinity felt by many people here there will be a deep sense of loss at her passing."
The Northern Ireland Secretary, Dr John Reid, said she had touched the hearts of generations in the province.
"I know that the Queen Mother had a special fondness for this part of the United Kingdom and that was reciprocated by the deep affection of so many in Northern Ireland for her gentleness and warmth.."
The DUP leader, the Rev Ian Paisley, said: " She was not just a friend of Northern Ireland but a personal friend. Her death is all the more sorrowful coming so soon after the death of her daughter Princess Margaret."
The Presbyterian Moderator, Dr Alastair Dunlop, said: "The Queen Mother was a lady of strong Christian faith which marked every aspect of her life."
Dr Samuel Hutchinson, Clerk of the Presbyterian General Assembly commented: "The Queen Mother was one of those people who instantly makes a lasting impression."
Many of the tributes centred around her role during second World War, when the royal couple refused to leave London under Nazi German bombing.
"In Russia people knew Her Majesty well, and highly valued her contribution to the collective efforts of the anti-Hitler coalition, and to strengthening allied relations between our countries during the years of World War Two," the Russian President, Mr Vladimir Putin, said in a message.
"Her Majesty commanded the sincere love and respect of the British people and of millions of people across the whole world," the Russian leader added in the message released by the Kremlin.