Eurostar is set to carry more than 110,000 passengers between the opening of St Pancras International on November 14 and Christmas.
Tickets to travel on High Speed 1 – the UK’s first 186mph line – went on sale on July 24.
In the first two weeks of sales, advance bookings are more than double the same period last year, with demand coming from both business and leisure travellers.
High Speed 1 will cut journey times by at least 20 minutes, taking passengers to Paris in two hours 15 minutes and Brussels in one hour 51 minutes.
Eurostar chief executive Richard Brown said: “We are seeing a huge surge in advance bookings for travel on High Speed 1. It’s evidence that the public is excited by the prospect of journeys that are at 20 minutes quicker, the experience of travelling at 186mph in the UK, and the desire to switch from flying in order to ‘do the right thing’ for the environment.