Recognition for opposition coalition includes right for member states to give military aid.
It is a seat that has been occupied by Bashar al-Assad for more than a decade, but the Syrian President's chair at the Arab League was handed to those seeking to oust him, in a historic moment for the opposition.
The three-starred flag of the Syrian revolution replaced the two-starred flag of the regime marking Syria's place at the two-day summit of the 22-member league in the Qatari capital, Doha.
Moaz al-Khatib, the moderate Damascus cleric who has steered the coalition since November, took the chair, making an impassioned call for help to end the two-year cycle of violence.
The symbolic move followed a tumultuous week for the Syrian National Coalition, fraught by resignations and infighting. Khatib was introduced to the assembled Arab leaders as the head of the opposition coalition, despite dramatically quitting his post at the weekend.