The United States, Britain, Malaysia and other countries welcomed the accord.
"This agreement is a testament to the commitment of all sides for a peaceful resolution to the conflict in the southern Philippines," U.S. Secretary of State Hillary Rodham Clinton said in a statement. "The next steps will be to ensure that the framework agreement is fully implemented."
The new Muslim region would be built upon an existing five-province autonomous territory, among the country's poorest and most violent, with more than 4 million people.
The Moro rebels earlier dropped a demand for a separate Muslim state and renounced terrorism.
Their negotiator, Mohagher Iqbal, earlier said his group would not lay down its weapons until a final peace accord is concluded. He said the insurgents could form a political party and run in democratic elections to get a chance at leading the autonomous region for which they have been fighting.
In Kuala Lumpur, Philippine government negotiator Marvic Leonen said both sides face the enormous task of working out the details. "We are not naive to say that there would be no obstacles. But the Philippine government will defend the agreement," Leonen said.
The challenges are many.
In 2008, the planned signing of a similar preliminary pact was scuttled when opponents went to the Supreme Court, which declared the agreement unconstitutional. Fighting erupted when three rebel commanders attacked Christian communities, and an ensuing military offensive killed more than 100 people and displaced about 750,000 villagers before a cease-fire ended the violence.
One of the hardline rebel commanders, Ameril Umbra Kato, broke off from the Moro rebels last year and formed a new group opposed to the talks. Kato's forces launched attacks on several army camps and outposts in August, prompting another army offensive that killed more than 50 fighters in the 200-strong rebel faction.
The Moro Islamic Liberation Front itself broke away in the 1980s from the Moro National Liberation Front, which signed a 1996 autonomy deal with the government. That peace accord did not lead to disarming of the group and many of the rebels have simply laid low in the south, still demanding that the government fulfill its commitments, including jobs, security and economic development.
Some former guerrillas also formed a small but brutal al-Qaida-linked group called the Abu Sayyaf, which became notorious for bombings, ransom kidnappings and beheadings until U.S.-backed Philippine military offensives routed many of its militants. They are mostly based in the southern provinces of Sulu and Basilan, where about 400 gunmen remain.
Ng reported from Kuala Lumpur, Malaysia. Associated Press writer Hrvoje Hranjski in Manila and Matthew Pennington in Washington, D.C., contributed to this report.