According to a statement, the accord was signed on Friday after two days of talks in Ghana's capital Accra.
Under the terms of the deal, rebel forces holding the north of the West African country will start disarming by 15 October after political reforms, which were first agreed on in a January 2003 peace agreement, are implemented by the end of August.
Ivory Coast's conflict mushroomed out of a coup attempt in September 2002. Although a peace deal was struck four months later and hostilities declared over in July 2003, the country has remained mired in an uneasy stalemate.
The statement said Ivory Coast President Laurent Gbagbo had pledged to use his constitutional powers to push through an amendment to an article in the constitution which prevents an opposition leader from running for head of state.
A million uprooted
A dozen African presidents attended the summit in Ghana to pressure Gbagbo and rebels, known as the New Forces, to strike a deal and bring an end to a civil war in which thousands died and more than a million people were uprooted from their homes.
"Ivory Coast is so strategic in the affairs of Africa and especially West Africa that we all thought we should not sit by and let a sister nation fail," Ghana's President John Kufuor told a news conference.
Between the two sides are 4,000 French soldiers and another 6,240 troops sent by the UN, mainly from Pakistan and Morocco, who are policing a confidence zone around the ceasefire line which bisects the nation.
UN Secretary General Kofi Annan said a power-sharing government, which has effectively been defunct since opposition and rebel ministers walked out this year, would resume work unchanged with a cabinet meeting to be called within a week.
The crisis has disrupted Ivory Coast's once powerful economy, underpinned by cocoa, rubber, coffee, palm oil, timber and cotton, and has also deprived landlocked neighbours such as Mali and Burkina Faso access to its two Atlantic ports.