The peacekeepers are to monitor a crucial agreement signed in January between the Khartoum government and southern rebels that ended a 21-year old civil war. That conflict cost two million lives and forced four million people from their homes.
The council's resolution on Thursday, drafted by the United States, calls for up to 10,000 military personnel and a civilian component of up to 715 police.
UN officials say such a force will take several months to get on the ground.
In their accord, Khartoum and the Southern Peoples Liberation Movement agreed on political power-sharing arrangements and a division of country's oil wealth.
They also called for integrated security forces in southern Sudan, the Nuba Mountains, the Southern Blue Nile and in Khartoum.
In six years, southerners, mainly Christians and animists, would be entitled to a referendum to determine whether they wanted to form their own state and break from the Islamic-dominated north.
But Security Council members remained deadlocked over imposing sanctions on Darfur - and where to try perpetrators of atrocities with France having introduced a resolution to send war crimes suspects to the International Criminal Court, which the United States opposes.
The Darfur crisis has not been
resolved, to the UN's chagrin
France on Thursday delayed a vote on the court until next week to give delegations more time, especially the US. European diplomats still hope to get an abstention from Washington, although that appears unlikely.
The Bush administration rejects the court, the world's first permanent criminal tribunal set up in The Hague to try war crimes, genocide and crimes against humanity. It fears US citizens could face politically motivated prosecutions.
A US veto could, in effect, send a signal to Sudan that its officials, militia leaders and rebels were safe from punishment in Darfur, where fighting is escalating, tens of thousands have been killed and some two million people have been herded into squalid camps.