Riviere, 24, made 30 appearances for Monaco last season and scored 10 goals.

His arrival at St James' Park comes after the club saw loan signings Loic Remy and Luuk de Jong as well as out-of-contract Shola Ameobi leave the club.

Papiss Cisse, meanwhile, is recovering from a knee injury.

"This is an important signing because we know that in the striking department, with Papiss injured, we need to improve that area," said Newcastle manager Alan Pardew.

"We have looked at Emmanuel for a while and we know he will score goals for us. He is quick, hungry for success and will love having 50,000 Geordies cheering him on."