The half-back joined the club at the start of the campaign on a trial basis, and has played in the first two Championship games for Rovers.
The move is now subject to clearance from the French Rugby League Federation.
“I feel good at Featherstone Rovers and I’m settling in well,” said Marginet.
“I like playing for my head coach Andy Hay and the systems he plays.
“Featherstone is a very good club with quality players and my ambition is to help Rovers finish in the top four of the Championship.
“I’m getting to know my teammates and I really like playing rugby league in Yorkshire as the fans are very close to the pitch which creates a good atmosphere.”
Rovers coach Andy Hay is optimistic that the Frenchman can play a prominent role for Fev for the rest of the season.
“Remy has been really impressive in his trial period at the club and I’m pleased to say that he wanted to make the switch on a permanent basis,” he said.
“He needs to get to grip with some of our plays but he will be a useful addition to our squad for 2015.”