The company, owned by Stagecoach, have started selling tickets to destinations including Paris, Boulogne, Brussels and Amsterdam.
The tickets, which include ferry crossing and free on-board wi-fi, cost between £1 and £40, although fares under £4 are elusive.
The journey time won’t rival the Eurostar, with trips from London Victoria Coach Station to Porte Maillot Coach Park in Paris taking 9 hours and 15 minutes.
The company is also considering launching a sleeper service between Britain and Europe, and is discussing suitable vehicles with Belgian manufacturer Van Hool.
The first European-bound Megabuses left Victoria on Monday morning, heading for Paris and Brussels.
Stagecoach chief executive Sir Brian Souter said bookings were currently “going gangbusters”.
The main competitor, Eurolines, owned by National Express, recently offered promotional fares for around £10.