The centre-back arrived at St James’ Park in January 2013 after carving out a reputation as one of Ligue 1’s best talents with Montpellier.
However he has struggled in the black and white shirt in the North East, failing to hold down a first-team berth under Alan Pardew.
In one of the rare games he was entrusted with a start last term, Yanga-Mbiwa saw red for hauling down Liverpool’s Luis Suarez.
A fee is yet to be agreed between the two clubs, but with the 25-year-old having settled personal terms it appears unlikely that the Magpies will put up a fight.
The £7m paid for the player 18 months ago is unlikely to be recouped, with St Etienne due to shell out only half of that.
The enforcer is set to replace Kurt Zouma, who recently made his move to Chelsea official.