Open Doors UK was speaking after Nigerian soldiers found Amina Ali Nkeki was pregnant, traumatised and wandering in the north-eastern Sambisa Forest on Tuesday night.
Amina Ali Nkeki was one of 276, mostly Christian, girls kidnapped from a boarding school in the Nigerian town of Chibok in 2014 by the Islamist group Boko Haram.
Dozens managed to escape within days of their abduction however 219 of them remained captive with Boko Haram; Amina Ali Nkeki is the first of them to be recovered.
It is not known how many thousands of girls, boys and young women have been kidnapped by Boko Haram in a nearly seven-year-old insurgency that has killed some 20,000 people and spread across Nigeria's borders.
Nigeria's military has reported freeing thousands this year as they have forced the extremists from towns and into strongholds in the sprawling Sambisa Forest.
Community leader Pogu Bitrus says other Chibok girls may also have been rescued by soldiers hunting down Boko Haram in the Sambisa Forest after they found Amina Ali Nkeki.
Mr Bitrus said he was working with officials to establish their identity.
Speaking to Premier about the latest development, Beth Fuller, from Open Doors UK, said: "We've just been praying for these girls for two years really hoping for their release, hoping that they're safe and alive and can be reunited with their families."
"So hearing that one of them has been found is just incredible news and a real answer to prayer."
Listen to Premier's Marcus Jones speaking to Beth Fuller: