"After several months of intensive care, the team is overjoyed to repatriate these protected animals to Madagascar," said a statement from Tortoise Village in France's southeastern Var region.
The centre took in the tortoises after they were found in the secret compartment of a crate transporting sea cucumbers through Charles de Gaulle airport in December.
The species -- known as "radiated tortoises" -- are found only in Madagascar and prized by collectors for the unique pattern on their shell case.
They can live up to 100 years, but are listed as critically endangered by the International Union for Conservation of Nature (IUCN) which estimates they could be extinct within 50 years as a result of habitat loss and the international wildlife trade.
Around 20 of the baby reptiles died during the trip to France due to the "particularly unsuitable conditions of transport," customs officials said at the time, adding that they were destined for Laos.
Bernard Devaux, director of the Tortoise Village, described them at the time as "magnificent but very fragile."
Weighing only 20g (0.7 ounces) and measuring up to four centimetres (1.5 inches) they were too small to face a second international flight straight away.
But the centre said Tuesday they were now in good shape and had gained between 40 and 60 percent in weight. They are due to fly home on August 24.
"They are considered the most beautiful tortoises on the planet. You see them sold for $10,000 in New York or Tokyo and pressure is increasing as rich Chinese get involved," said Devaux when they were found.
"They represent too much money. They are beautiful so they are hunted. Maybe it would be better if they were ugly."