White, 24, played for the French club in the Championship in 2011, but spent last year playing rugby sevens and rugby union.
He said: “I am grateful and delighted to be able to focus on being of the plans of coach Giles Dumas.
“There’s a significant opportunity to assist in the development of the club, and being a small part of the raising of rugby league’s profile as a major sport in France, as well as personally aiming towards a place in the French squad.
“Adam Innes is retiring after many seasons in France and Toulouse. The opportunity to replace him came up. I do not doubt that I will need to work hard to fill Adam’s shoes, but I’m confident with the right attitude I can bring the “goods” to the club.”