The 33-year-old, who won the Champions League with Inter Milan in 2010, was a free agent after leaving Galatasaray at the end of last season.
The former Ajax, Real Madrid and Inter Milan has signed a one-year deal, the club said.
Sneijder played in the 2010 World Cup final for the Netherlands and has won league titles in four countries.
Nice finished third in Ligue 1 last season and face a two-legged play-off against Napoli later this month to qualify for the Champions League group stages.
On Saturday they lost their opening league match of the season 1-0 to Saint-Etienne.
Netherlands midfielder Wesley Sneijder has joined French Ligue 1 side Nice on a free transfer.