Sneijder completed his move early on Monday and was out on the training ground just a few short hours later.
The veteran was met by a baying crowd and even flares as his new fans welcomed him to the club.
The 33-year-old joins up with former Inter Milan team-mate Mario Balotelli in France, with fans hoping the duo can forge a productive partnership.
The former Real Madrid midfielder joins Nice on a free, having been released by former club Galatasaray at the end of last season.
Sneijder will add some much-needed creativity to Lucien Favre’s side, who were beaten 1-0 by Saint-Etienne at the weekend.