French police in the Alpine town of Bourg Saint-Maurice said the boy was skiing off piste in a group of seven skiers on Wednesday when he was swept away and buried.
His rescuers described finding him unhurt after 40 minutes in the snow as a true “miracle”.
The incident happened when the boy started going down the mountain ahead of the others in his group.
He was the only one caught when a large section of snow detached and roared down the mountain, police said.
He was dragged at least 100 metres by the force of the avalanche.
Rescue workers flew in a helicopter to the avalanche scene, which was at an altitude of 7,875 feet.
A sniffer dog found the boy, whose winter jacket was not equipped with an avalanche detector.
Rescue workers described the operation as “miraculous” because they said chances of survival are minuscule after 15 minutes under the snow.
Police said one of the reasons the boy survived was that his airways were not blocked by snow.
“We can call it a miracle. A day after Christmas, there was another gift in store,” Captain Patrice Ribes told AP.
The boy was still sent to a local hospital for a checkup.
Additional reporting by AP
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