The 263-seater monohull is due to start service next June on the Granville to Jersey to Sark and the Carteret to Guernsey routes.
It will complement the Marin Marie and the Victor Hugo, which already sail to the Islands daily during the summer.
The boat is being built in La Rochelle and has been designed especially to cope with Channel Islands waters.
It has also emerged that Manche Iles Express may start using the main Elizabeth Terminal at St Helier harbour instead of passengers boarding from the Albert Pier.
This would enable the ferries to remain in port at low tide.
The two boats already operating on the route are owned by the Normandy municipal body the General Council of La Manche and are operated by Manche Iles.
The Marin Marie seats 243 and the Victor Hugo 195.
So the new ferry would bring the capacity of the service to 700 passengers.