The 25-year-old will formally complete a Bosman free transfer move to St James' Park on July 1 after signing a five-year deal.
Toon stepped in for Marveaux after Liverpool dithered over a disappointing medical.
The Magpies carried out their own checks and are confident that will not be an issue, and have snapped up their third close-season signing.
Newcastle boss Alan Pardew said: "It's a great coup to have signed Sylvain, who has received interest from a number of other clubs.
"He may not be well known to many of our fans, but he is a real talent and a player we have been keeping an eye on for some time.
"It's been a good couple of days for us on the transfer front."