The Omani foreign ministry said the release of Nourane Houas was secured "at the request of the French authorities, the instructions of Sultan Qaboos and in coordination with Yemeni parties", which it did not identify.
The International Committee of the Red Cross (ICRC) in Yemen confirmed in a tweet that their colleague had been freed.
Houas, a staffer with the ICRC's humanitarian protection programme in Yemen, was abducted in the Houthi rebel-held capital Sanaa in early December 2015.
Online footage that surfaced on May 6 showed Houas appealing to her Red Cross employers and governments to help free her. The 39-second video, which was shared on Yemeni news sites, showed Houas wearing a black veil and pleading in French to President Francois Hollande and Yemen's exiled president, Abd-Rabbu Mansour Hadi, for assistance.
Source: National News Agency