Byway will arrange the train travel and any accommodation along the route and overnight stays can be included in cities such as Paris, Verona or Turin.
The partnership comes following an increase in demand from customers wanting to extend their Exodus holiday with overnight stays in European cities. Train travel, Exodus said, also has a much lower carbon impact than travel by plane or car.
Exodus offers the 12-day Highlights of the Dolomites itinerary, which includes a night in Turin on the way out and extra nights in both Venice and Paris on the way back, for £1,349pp.
Meanwhile, the 10-day Mont Blanc Highlights trip starts from £1,449pp and includes B&B accommodation, five lunches, six dinners, snacks, transport, listed activities and a tour leader throughout.