During her three-day visit, the Oscar-winning actress met unaccompanied children living in the eastern Bekaa Valley, where many of the poorest Syrian refugees in Lebanon reside.
"Lebanon, as you know, has the highest concentration of refugees of any country in the world in recent history; it is an extraordinary thing and we must do all what we can to support them," said the United Nations Refugee Agency Special Envoy.
"I spent time in the Bekaa Valley recently with Syrian refugees and they are very grateful to the people of Lebanon, they are clearly very traumatised from what has happened to them in Syria," the 38-year-old added.
The Hollywood actress and UN special envoy also met with the prime minister of Lebanon, the tiny Mediterranean country which neighbours Syria, Tammam Salam.
The meeting was to call on the international community to ensure the implementation of a recent U.N. resolution that called for humanitarian assistance to reach Syrian civilians, as well as to thank Lebanon for hosting nearly one million refugees, which has increased the small country's population by one fifth.
Angelina speaking during a news conference after meeting with Lebanon's Prime Minister Tammam Salam
On Saturday, the UN Security Council passed a resolution dem anding immediate access everywhere in Syria for humanitarian aid.
'Meeting these children was a heart-rending experience,' said Angelina in a statement issued via the U.N.
'They have lost their families and their childhood has been hijacked by war. They are so young, yet they are bearing the burdens of their reality as if they are adults.'