The Allosaurus, a ferocious carnivore named Kan whose species went extinct some 135 million years ago, fetched 1.1 million euros, Aguttes said.
Discovered in 2013 in the Jurassic Era Morrison Formation in the western United States, the specimen is more than 7.5 metres (25 feet) long and 2.5 metres tall.
The unnamed buyer is French and the skeleton will remain in France and go on public display, an Aguttes spokesman said,
without revealing when or where the unveiling would take place.
The buyer, who made the purchase by telephone, "wants to keep the location a surprise", the spokesman said.
The skeleton is three-quarters complete and shows Kan in a running position with its mouth open.
The auction house described the beast as "the archetype of the great predators of the Jurassic Era".
The sale fell short of the 1.3 million euros fetched by a dinosaur skeleton in October 2010 at Sotheby's in Paris.