Fifteen aid trucks have reached the besieged Damascus suburb of Eastern Ghouta with foodstuff and medical supplies.
The city has been pounded by a devastating civil war.
Social media videos uploaded by Syria’s Smart News Agency shows a long convoy of United Nations and Red Crescent vehicles making their way through city streets punctuated with rumble.
In the video, bags with the World Food Programme logo are also seen being carried into a building.
A UN statement on Tuesday said there were plans to deliver supplies to areas controlled by the opposition which had been blocked by government forces.
The announcement came at a time Damascus had accepted a U.S.-Russian plan for a “cessation of hostilities” with rebels expected to take effect from February 27.
The ceasefire announcement came after intense talks to stop the five-year-old Syrian conflict.
There are fears that the exclusion of the Islamic State and Nusra (a group linked to al-Qaeda) in the ceasefire deal could force the government to escalate attacks on the militants.