The 20-year-old has joined the Magpies on a permanent basis, and will link up with Neil Redfearn's under-23s squad.
Francillette has spent time with Dijon and has also represented Guadeloupe internationally at youth level.
“I'm very happy to be here," he told nufc.co.uk. “It's an honour to sign with this club, because we know the story with French players playing for Newcastle, and the fans, and I'm very happy to sign. I hope everything will be good.
“It's a Premier League, a big club in the Premier League, which is the best league. I have seen a lot of games – I like the club and I like the city too.
“The fans love the club, and the fervour. If I give 100 per cent, the fans will give 110 per cent. I enjoy the proximity of the fans to the club.
“I want to progress in training, work hard and focus now."