Leaders from the three main parties to the pact met before a session of parliament on Saturday and agreed to reconcile their differences and address the protests of the Sunni-backed bloc led by former premier Iyad Allawi.
MPs passed the deal by consensus, a parliamentary official told AFP, and an Iraqiya member read a statement to the Council of Representatives explaining why around 60 lawmakers from his bloc had walked out.
"We left because of a misunderstanding over the implementation of the agreement," Haidar al-Mullah, an Iraqiya MP said in a statement to the chamber.
The official, speaking on condition of anonymity, added that "around 250 MPs (of 325 members) who were present approved by consensus the power-sharing initiative."
It was not immediately clear why 75 MPs stayed away from the session, or whom they represent.
Mullah said later that three senior Iraqiya members who were barred from standing in the March elections over their alleged ties to ex-dictator Saddam Hussein's Baath party would be reinstated within 10 days.
Parliament's failure to do so on Thursday prompted the walk-out.
The next session of the Council of Representatives is scheduled for November 21, with the prolonged break due to next week's Eid al-Adha holiday.
The power-sharing deal called for Maliki, a Shiite, and President Jalal Talabani, a Kurd, to keep their jobs and for a Sunni Arab to be selected speaker of parliament.
It also established a new statutory body to oversee security as a sop to Allawi, who had held out for months to regain the post of premier.
The support of Allawi's Iraqiya bloc, which narrowly won the March 7 poll and garnered most of its seats in Sunni areas, is widely seen as vital to preventing a resurgence of inter-confessional violence.
The Sunni Arab minority that dominated Saddam Hussein's regime was the bedrock of the anti-US insurgency after the 2003 invasion.
Thursday's parliamentary session, only the second since the election, had got off to a good start, with Maliki and Allawi sitting side-by-side in the chamber.
But shortly after Sunni Arab and Iraqiya member Osama al-Nujaifi was chosen as speaker, verbal clashes erupted, with Iraqiya complaining that the deal was not being honoured.
Iraqiya had wanted the three barred members to be reinstated before the vote to elect the president.
When their demands were not met, around 60 lawmakers left the chamber. After some confusion, the remaining MPs began voting to re-elect Talabani.
Iraqiya has said its participation rests on four conditions: a bill forming the security body, a committee examining cases against political detainees, codifying the power-sharing deal and annulling the bans on the three Iraqiya members.
Allawi has repeatedly accused Maliki of monopolising security decisions during his first term. As far back as six months ago, US officials floated the idea of a new counterweight to the premier's office in order to break the deadlock over the top job.
US President Barack Obama hailed the agreement as a "milestone" in Iraq's history.
The government would be "representative, inclusive and reflect the will of the Iraqi people," he said, adding that Washington had long lobbied for such a "broad-based government."
The US military, which currently has fewer than 50,000 soldiers in Iraq, is due to withdraw all of its forces by the end of 2011.
Britain, a partner in the US-led invasion, called the deal a "significant step forward," a sentiment echoed by France and Iraq's northern neighbour Turkey.
UN chief Ban Ki-moon welcomed the deal but urged Iraq's leaders to "continue demonstrating the same spirit of partnership in moving swiftly to conclude the formation of a new government."
The Security Council said it "encourages Iraq's leaders to rededicate themselves to the pursuit of national reconciliation," and emphasised the importance of Iraq's stability for the region.
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