In a statement following the end of a judicial investigation, the Paris-based prosecutors' office did not disclose the identity of the suspects.
Four suspects have been charged with terrorist conspiracy for alleged links to the attacker, Mohamed Lahouaiej Bouhlel, who plowed a 19-ton truck down Nice’s Promenade des Anglais and into a crowd assembled for the July 14 fireworks display.
Five other suspects have been charged with other criminal charges, including for allegedly providing arms to the assailant. The prosecutor's office said they likely did not have knowledge of what Bouhlel intended to do with them.
One of these five suspects remains at large and is being searched for under a criminal arrest warrant.
The trial, which is set to take place at a special court for terrorist cases in Paris, is not expected before the end of next year.
The Islamic State group had claimed responsibility for the July 14, 2016, attack. French authorities said Bouhlel, a Tunisian with French residency, was inspired by the extremist group’s propaganda, but they say no evidence has been found that IS orchestrated the attack.