Work is ongoing at stations in Amsterdam and Rotterdam to build passport and security clearance facilities.
The journey will take three hours and 41 minutes from city to city. Passengers embarking in the Netherlands will travel with Thalys up to Brussels Midi station, where passport and security checks will be conducted, before embarking on a Eurostar train for London. That trip will take approximately four hours and fo minutes.
Eurostar is launching the service with two trains a day from St Pancras International to Amsterdam city centre.
After extensive preparation, a comprehensive programme of testing on the Dutch high speed network and the building of Eurostar terminals in Amsterdam and Rotterdam, Eurostar's new route to the Netherlands will start on 4 April 2018 with one-way fares from £35.
Harrison is Mixmag's East Coast Editor.
The trains from London to the Netherlands will depart at 8.31am and 5.31pm on weekdays, then 8.31am Saturday and 5.31pm on Sunday.
About 4 million people now travel between London and Amsterdam by air, and Eurostar said it's targeting a significant share of that market. It says the market for travel between London and Paris has more than doubled as passenger increasingly choose high-speed rail over the plane.
Eurostar's chief executive, Nicolas Petrovic, said: "The launch of our service to the Netherlands represents an exciting advance in cross-Channel travel and heralds a new era in worldwide high speed rail". However, Eurostar says this will be a temporary process while the governments of the United Kingdom and Netherlands negotiate an agreement to enable passport checks to be carried out in the Netherlands.
These issues mean direct services returning to London will not be in place until the end of next year.