Salah el-Makhzoum, a vice president of the Tripoli-based parliament, called this a "happy day" in announcing the accord will be signed December 16.
An official of the internationally recognised parliament, Mohammed Choueib, said that "after lengthy efforts... We announce to our people that we have decided to move beyond this difficult period... And ask everyone to join us".
Choueib said the deal could be signed in Morocco, which hosted most of a year of talks brokered by UN envoy Leon Bernardino that led to the proposed deal in October.
And just Sunday, delegates from both sides announced they had reached a joint "declaration of principles" aimed at resolving a crisis after secret talks that did not include the UN.
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Under the UN-brokered deal, Libya would be governed by a nine-member presidential council comprising a prime minister, five deputy premiers and three senior ministers.
Libya descended into chaos following the 2011 ouster and killing of long-time dictator Moamer Kadhafi.
Hundreds of protesters gathered in Tripoli's main square today afternoon, waving Libyan flags and holding signs calling for a rejection of the UN deal and backing the one reached at the weekend.
They were called onto the streets by Libya Dawn, the Islamist militia coalition that is a key backer of the Tripoli government.
Demonstrator Abdel Hamid Zawawi said: "After I saw that the EU countries and the US are insisting on the UN deal, I was convinced (it) should be out of the question."
Today's announcement comes just two days before world leaders are set to gather in Rome to try to speed up the formation of a unity government in Libya, where chaos is fuelling the rise of the Islamic State group.