But opposition activists in Homs expressed scepticism, saying they first wanted aid supplies and "guarantees" that those leaving would not be arrested.
"What we have been told by the government side is that women and children in this besieged area of the city are welcome to leave immediately," Brahimi told reporters after a second day of talks involving regime and opposition delegations in Switzerland.
He said this would be "hopefully starting tomorrow" and that other civilians would also be allowed to leave "but the government needs a list of their names first."
The subject of Homs -- where hundreds of families in the Old City are living under siege with near-daily shelling and the barest of supplies -- has been discussed at length since the two parties started face-to-face talks on Saturday.
Brahimi also repeated his hope that a convoy of humanitarian aid could enter the besieged area on Monday, saying rebel forces had already agreed and the local governor was considering the issue.
Syrian Deputy Foreign Minister Faisal Muqdad confirmed that women and children would be allowed to leave and blamed rebel forces for preventing it in the first place.
"I have been personally involved over the past two years to get these women and children out of the Old City of Homs... In all these attempts we have been prevented by the armed groups, who did not allow a single person out," Muqdad told reporters.
From inside the area, a spokesman for the Syrian Revolution General Commission activist network, Abu Rami, said residents had "no trust in the regime" and wanted guarantees from the UN or International Committee of the Red Cross.
"We are calling for significant amounts of food and medical supplies, and for guarantees that women, children and wounded people evacuated from Homs' besieged areas will not be detained," he said.
Pulled together by the United Nations, Russia and the United States, the two sides are meeting in the biggest diplomatic push yet to stem Syria's bloodshed after nearly three years of civil war.
Focus on prisoner exchanges
Talks on Sunday also touched on the thousands of people jailed, kidnapped or missing in Syria and efforts to negotiate prisoner exchanges.
The opposition said it had a preliminary list of 47,000 people held by the government, including 2,300 women and children whose names it had submitted.
"If there is an exchange, women, children and the most vulnerable will be the priority," opposition spokesman Monzer Aqbiq said.
Syrian Information Minister Omran al-Zohbi said the issue of prisoners needed to be discussed "without discrimination", with the focus also on people held by rebel forces.
"There are also thousands of people who have been kidnapped, some who have been missing without a trace for two-and-a-half years," he told reporters.
Brahimi said the opposition had agreed "they will try to collect a list of names" of people held by rebel forces they control or have contact with.
The Syrian Observatory for Human Rights, a key watchdog, estimates that some 17,000 people have gone missing in the war, tens of thousands are being held in government jails and thousands kidnapped by armed groups including Islamist militias.
With little hopes of major political breakthroughs at the talks, mediators are focusing on short-term deals to keep a peace process moving forward, including on localised ceasefires, freer humanitarian access and prisoner exchanges.
But the opposition has said it wants the talks on Monday to move to the core issue of a political transition.
It insists the discussions should focus on Assad leaving power and the formation of a transitional government based on an agreement reached during a first peace conference in Geneva in 2012.
The regime says Assad's role is not up for debate at this conference -- dubbed Geneva II -- and denies that the initial Geneva deal requires him to go.
Brahimi did not confirm that political issues would be discussed on Monday but said the talks would become more general.
"This is a political negotiation, everything we discuss is political," he said. "I think tomorrow I expect the two parties to make some general statement about the way forward."
Erupting after the regime cracked down on protests inspired by the Arab Spring, Syria's civil war has claimed more than 130,000 lives and forced millions from their homes.