"Finally he is returning home," US Secretary of State John Kerry said in a statement, confirming the release of Peter Theo Curtis, a 45-year-old author and freelance journalist whose disappearance in Syria had not been previously reported.
Curtis was handed over to UN peacekeepers in the village of Al Rafid, Quneitra, in the Golan Heights and after undergoing a medical checkup was turned over to US representatives, the United Nations said.
The news of his release came less than a week after a video surfaced showing the slaying of captive US journalist James Foley at the hands of an Islamic State militant.
"Particularly after a week marked by unspeakable tragedy, we are all relieved and grateful knowing that Theo Curtis is coming home after so much time held in the clutches of Jabhat Al-Nusrah," Kerry said referring to the Al-Nusra Front, another Islamic rebel group operating in Syria.
Kerry said the United States had reached out to more than two dozen countries for help in securing Curtis' release, and that of any other American held hostage in Syria.
Kerry's statement said Curtis' mother had "worked indefatigably to keep hope alive that this day could be a reality."
US National Security Adviser Susan Rice said she expected Curtis to be reunited with his loved ones shortly.
Curtis's family thanked both the governments of the United States and Qatar, as well as others who helped negotiate his release.
"My heart is full at the extraordinary, dedicated, incredible people, too many to name individually, who have become my friends and have tirelessly helped us over these many months," his mother Nancy said in a statement.
"Please know that we will be eternally grateful," she said, asking for privacy.
According to the family's statement, relayed to reporters via the State Department, Curtis was captured shortly before he crossed into Syria in October 2012 and was held since then "by the militant group Jabhat al-Nusra or by splinter groups allied with Jabhat al-Nusra".
Describing his as an author and freelance journalist from Boston and Vermont, the statement said Curtis writes under the name Theo Padnos and is a freelance journalist and published author from Boston and Vermont.
- Foley's fate recalled -
Curtis' mother, in her comments, recalled Foley's fate, saying she got to know the late journalist's family.
"We are so relieved that Theo is healthy and safe and that he is finally headed home after his ordeal, but we are also deeply saddened by the terrible, unjustified killing last week of his fellow journalist, Jim Foley, at the hands of the Islamic State in Iraq and Syria," she said.
Rice also referenced Foley's killing, which she said "shocked the conscience of the world," and said the United States "will continue to use all of the tools at our disposal to see that the remaining American hostages are freed."
"We will continue to work tirelessly on behalf of all Americans who are held overseas so that they can be reunited with their families as well," Rice said
Foley's family, meanwhile, offered prayers for the safety of is fellow hostages in Syria on Sunday as they prepared to take part in a memorial mass his home town of Rochester, New Hampshire.
Before the service, they told AFP that they hoped their son's legacy would be an inspiration to others supporting a free press and an end to suffering in war zones.
"James stood for love and hope," Diane Foley told AFP at the family's suburban home, where James' brothers and sister had gathered.