Syria State television said the army raised the flag near the post office on Thursday, the only government building in the portion of the city that had been held by rebels.
Government forces backed by Russian air attacks have recovered swaths of southern Deraa province in the last three weeks, advancing unopposed by Syria's western and regional foes into the strategically vital region near Jordan and Israel.
It marks another milestone in Syria's efforts to recover control of the country.
Numerous towns in the southwest had already struck their own surrender deals with Syrian government.
The crisis in Syria, which flared in March 2011, has so far claimed the lives of hundreds of thousands of people and displaced nearly half of the Arab country’s population within or out of its borders.
