17 minutes quicker than the FlixBus coach to Orly (sold from €8.98), for up to €5.02 more. And no booking needed.
RER B and Orlyval to Orly
RER BOrlyval · RATP and Orlyval Service (RATP Dev), on one Île-de-France Mobilités airport ticketPickup, hours & luggage
Boards at. Aéroport Charles de Gaulle 2 TGV station under Terminal 2, or Aéroport Charles de Gaulle 1 at Terminal 3, then the Orlyval platforms at Antony
One EUR 14 airport ticket (Orlyval's own page, tariff of 1 January 2026) covers the RER B and the Orlyval; keep it for the gates at Antony. It is the same ticket as for the RER B into Paris, and no group or family fare exists.
Luggage. Carried, with a change at Antony; the RER has no racks and the shuttle is small.
Hours. Trains that call at Antony leave Terminal 2 from 05:05 and about every 10 minutes. The last that still meets the final Orlyval from Antony (23:35) leaves about 22:24 to 22:29. After that nothing links the two airports by rail.