Northern Ireland First Minister Peter Robinson reached a deal at midnight on Thursday with his party members to continue in government with Sinn Fein.
The British and Irish Prime Ministers, Gordon Brown and Brian Cowen, are expected in Belfast on Friday to witness the deal being inked. Both had flown to the North to take part in the negotiations late last week.
The deal will allow policing and justice powers to be devolved to Northern Ireland and a compromise has been reached on Orange parades marching through nationalist areas.
Peter Robinson stated his party had accepted the deal unanimously. Earlier in the week, 14 members of his 35-member assembly party were said to have rejected it.
However, a series of last minute negotiations were successful. Among them, apparently, was a decision by the British government to help unionists who invested in a church credit union that collapsed to get their funds back.
“We have had a very constructive meeting of our assembly group and I had the opportunity to put to them proposals which we have been working on," said Robinson.
"Everyone present believes that this is consistent with our election manifesto and pledges we have made to the people."
Sinn Fein President Gerry Adams said the DUP's decision had come after "a lengthy stretch of negotiations."
Praising his own party's negotiating team, he added: "I believe that the Assembly and political institutions can now proceed on the basis of equality, fairness and partnership.
"They also have to deliver for all citizens, that is the collective responsibility of all the political parties."
Robinson felt that the deal was a good one for all members of the DUP.
"An essential element of the Democratic Unionist manifesto is the requirement for community confidence and we believe that this can be the basis of gaining that confidence," he said.
"It does more than dealing with devolving further powers. It deals with how we deal with the powers that we have."
The DUP decision was welcomed by Alliance Party leader David Ford, who is expected to be the new justice minister.
"This is what the people of Northern Ireland have waited so long to hear and it means that the Executive can get back to the real work of providing quality services and strengthening our economy, " said Ford.
"We may face a few challenges in the coming months as regards the justice devolution process, but I am very hopeful that this will signal a new, more positive era for Northern Ireland."
However, Traditional Unionist Voice spokesman Jim Alistair described the DUP as "snowmen who had melted" under the pressure to get a deal.