The Gaelic Athletic Association (GAA) today abolished the controversial Rule 21 at a specially convened Congress at the City West Hotel in Dublin.
The rule had prohibited members of the North's security forces and British military becoming members of the GAA.
The GAA's decision was "warmly welcomed" by the Government.
The Taoiseach Mr Bertie Ahern said he knew the decision had been a difficult one for some people and had followed an intense debate.
He added: "There have been many divergent views on this issue, but I believe the association has conducted the debate in the most democratic way possible.
"I want to salute delegates for their vision and their commitment to the further development of Gaelic games on this island.
"The Good Friday Agreement and the policing arrangements that are being put in place in Northern Ireland are creating the environment where nationalists and unionists can live together on the basis of partnership, equality and mutual respect.
"The deletion of Rule 21 is very much consistent with this new beginning and with promoting reconciliation and tolerance in Northern Ireland."
Delegates voted with a show of hands and the motion was passed by an overwhelming majority. GAA Congress requires a two-thirds majority to pass all motions.
The rule was introduced in 1887 and then revoked in 1900. It was reinstated into the GAA rule book in 1903.
Significantly, Co Down was the only convention within the six counties to support abolition. Antrim, Armagh, Derry, Fermanagh and Tyrone were all opposed.
The Minister for Foreign Affairs Mr Brian Cowen welcomed today's move saying it was good for the GAA and good for the country. "Above all, it is good for those people, from North and South, who are considering a career in the new Police Service of Northern Ireland."
Mr Cowen added: "As a lifelong enthusiast of the GAA, both as a player, an administrator and as a supporter, I am delighted that the organisation is now truly open for all the people on this island."
Northern Ireland Secretary Dr John Reid also welcomed the GAA's decision.
Dr Reid said: "This is a progressive decision made by an association that played a large and important role in community life North and South.
"I welcome this contribution towards the creation of a more inclusive society."
Mr Michael McGimpsey, Sports Minister in the Stormont Executive, welcomed the move saying, "it comes at a time when we are moving forward on many fronts and will help us in our quest to build a conclusive society throughout Northern Ireland."
The Ulster Unionist minister, speaking from his party's annual conference in Belfast said he intended to take up a long-standing invitation to attend GAA events now that Rule 21 had been abandoned.
Former GAA President Mr Joe McDonagh attempted to remove the ban at special Congress in 1998, but after a lengthy debate the recommendation failed.
A decision was subsequently taken to leave discussions on the issue until "the time was right".
At that Congress, Ulster voted unanimously against removal of the ban but this year the province was split four to five on the proposal.
Co Monaghan - home county of current GAA President Mr Sean McCague - Co Cavan and Co Donegal signaled their intention to support abolition soon after the GAA's Central Council decided, on October 27th, to convene a special Congress.
The 26 counties south of the border supported abolition.
The Congress was held in camera.
Additional reporting PA