President Michael D Higgins is to become the first Irish head of state to make an official state visit to the UK.
The Queen formally invited the President and his wife Sabina to stay with the royals at Windsor Castle next April 8.
Aras an Uachtarain - the President's official residence in Dublin - has confirmed they have accepted the invitation.
The groundbreaking three-day State visit follows the Queen's hugely successful trip to Ireland in May 2011.
In remarkable scenes, the Queen paid her respects to republican dead at Dublin's Garden of Remembrance, visited Croke Park - site of the 1920 Bloody Sunday massacre - and made a widely-praised speech on Anglo-Irish history at Dublin Castle.
In what is considered a pivotal moment in relations between both countries, the invite to Ireland from former president Mary McAleese has paved the way for a reciprocal invite for her successor to the UK.
A number of meetings between Mr Higgins - a former Labour government minister, a poet and academic - and members of the Royal family have taken place since his election.
Both he and his wife met the Queen and the Duke of Edinburgh in June last year at Belfast's Lyric Theatre.
The President met Princess Anne at a sporting event while the Duke of Kent visited him this year at Aras an Uachtarain, the President's residence in Dublin's Phoenix Park.
Although the Irish head of state has travelled to events in London, Manchester, Liverpool and Scotland over the past year, these were not official visits.
Likewise, previous meetings between the Queen and President McAleese and her predecessor Mary Robinson at various functions in the UK were not official State visits.
Next year's trip will the first time an Irish head of state has been formally invited to the UK by a British sovereign.
Although the official programme is yet to be finalised, it is expected Mr and Mrs Higgins will stay at Windsor Castle and will pay official visits to the Prime Minister at Downing Street as well as the leader of the Opposition.
In line with other State visits to the UK, it is anticipated the Lord Mayor of the City of London will host a banquet for the President.
Sources said the programme will reflect the political, economic and cultural relations between the UK and Ireland.
A concert may also be held to mark the occasion. During the Queen's trip to Ireland, she was entertained by The Chieftains, Westlife, X-Factor singer Mary Byrne and Riverdance during an hour-long extravaganza at Dublin's Convention Centre.
It is also expected the Queen will host a State banquet for the President next April, during which both heads of state will make speeches.