International Rennes Airport (the airport is 9 km away from the Rennes railway station, a 15 mn ride by taxi), then take a train from Rennes to Saint-Malo (30 mn), or 45 mn by car)

An alternative is to fly to the Dinard Airport that is located 10 km from Saint-Malo. Ryanair flies to Dinard.

For more options to Saint-Malo by plane, visit this link.

TGV train from Paris Montparnasse to Rennes (2h00)

TGV train from Roissy Charles de Gaulle (CDG) airport to Rennes (2h15) Then train from Rennes to Saint-Malo (30 minutes).

TGV from Paris Montparnasse to Saint-Malo (direct - 3 hours)

Four hours from Paris, toward Rennes ("Direction Rennes")
For distances and times from various cities in Frances see this link .