The French Riviera is well-served by trains coming from other destinations in France although there is not (yet) a high-speed rail line directly to the heart of the Riviera. Here are the details:
From Paris, a TGV speeds to Marseilles or Avignon where it then slows down for the ride along the coast. (The old railroad tracks are not equipped for the fastest trains). The shortest amount of time is 5h41min to go from Paris to Nice taking a non-stop train. There are also trains that stop in Marseille, Toulon or Avignon before continuing on to all the coastal stops between Cannes and Monaco.
There's also one overnight train that takes about 12 hours to go from Paris to Nice with stops at Marseille, Antibes and Cannes. There are both seats and couchettes available. For the multi-bunk couchettes, sheets, a bottle of water, a sleeping mask, earplugs, towelette and a toothpaste tablet are included. Snacks and drinks are reasonably-priced and can be ordered on board to be delivered to your seat or bunk. Women can specifiy a women-only couchette at the time of booking.
Check schedules and buy tickets on thetrainline.
There are hourly trains from Marseilles to Nice. All except the TGV will make local stops. The trip takes a little over 2 1/2 hours. From Avignon, the TGV makes it to Nice in three hours; local trains take longer.Check schedules and buy tickets on thetrainline.
The TGV from Lyon to Nice takes 4hr32min; local trains take longer. Check schedules and buy tickets on thetrainline.
From the French Riviera to neighbouring Italy, there are a number of trains to Ventimiglia, just over the border, from where Italian trains take you to Italian destinations. All trains from the French Riviera to Italy involve a change at Ventimiglia.Check schedules and buy tickets on thetrainline.