Freelance reporters Massoud Aqeel and Farhad Hamo were on assignment for Rudaw in northeastern Syria when they were seized on December 15.
Aqeel "was freed yesterday as part of a prisoner exchange between Kurdish forces and Daesh," the Rudaw official said, using another acronym for IS.
"He spent the night in Tell Kocher under the protection of Kurdish fighters and he is now back in Qamishli," a large town in Syria's Kurdish area, near the border with Turkey.
Reporters Without Borders ranked Syria 177th out of 180 in its 2015 press freedom index.
According to the Paris-based watchdog, at least 30 journalists and online information providers are detained by the regime and at least 28 others are either missing or held hostage by armed groups, including IS.