Ghanaian centre-back Salisu, 21, has been in high demand following an impressive season with Valladolid.
Rennes agreed a €12m fee with Valladolid for Salisu back in June.
Southampton were said to be in pole position for Salisu, but he is now close to joining Rennes after all.
According to RMC, after much thought and discussion Salisu has decided to accept Rennes’ offer.
There are still a few details to finalise between Salisu and Rennes, who finished third in Ligue 1 this season.
Coupled with the recent arrival of Martin Terrier from Lyon for €12m, the Salisu signing will show Rennes’ ambition for next season.