French rescuers who found Darlene Etienne, 17, said it was a miracle that she had survived for more than two weeks trapped in the debris. She was shocked and dehydrated but happy to be free, they added.
"I don't know how she happened to resist that long. It's a miracle," said rescue worker JP Malaganne.
Etienne is believed to be one of the world's longest survivors of an earthquake.
"She just said 'thank you'; she's very weak, which suggests that she has been there for 15 days. She was in a pocket surrounded by concrete," Commander Samuel Bernes of the rescue team said.
Her family, which had assumed that she had died, said she had been studying at the College of St Gerard when the powerful earthquake struck on January 12.
Her discovery comes five days after the Haitian government officially announced the end of search and rescue operations.
Etienne's neighbours had been searching in the rubble of their home in the central Carrefour-Feuilles district when they heard a voice and alerted rescue teams.
The girl was trapped between a collapsed wall and a door and was able to lie down, rescuers said.
Etienne, who has an injury to her leg, was given oxygen and taken to a French-run field hospital for treatment.
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