The "CDG Express" is to be completed by 2023, the government said in an announcement in the Official Journal, on a budget of 1.6 billion euros ($1.77 billion).
The only current rail link to the airport, second in Europe only to London's Heathrow hub, is the "RER B" line, which doubles up as one of the French capital's busiest commuter services.
Photo: Ministry of Ecology
Passengers regularly complain about crowded trains with little room for luggage, too many stops, ageing carriages and a lack of security on the suburban line that runs through some of the Paris's poorest outskirts.
An earlier attempt at getting the CDG Express project going in 2006 was abandoned because of building challenges and political infighting.
Story continues below…
The express will connect the Gare de l'Est directly with the airport in under 20 minutes' journey time. They are expected to depart every 15 minutes and provide "absolute punctuality".