Eurostar carried 10 million passengers in a single year for the first time in 2013.
The high-speed channel tunnel rail service had originally expected to hit the 10 million passenger milestone by 1998 – four years after the launch of services.
The delay in reaching the 10 million passenger figure came as it faced competition from budget airlines, the global financial crisis and the London bombings in 2005.
Last year’s record means that 140 million passengers have travelled with Eurostar since services began in 1994.
Recent signs of a recovery in the UK economy along with a busy summer for leisure travel across its routes have helped Eurostar attract so many passengers in a single year, the company said.
Travellers from across Europe have joined an increasing number of international passengers from countries as far afield as the US, Australia, China and Brazil.
Eurostar commercial director Nick Mercer said: “2013 has been a record breaking year for Eurostar.
“With a leap in passenger numbers as well as the introduction of new routes and new destinations, we are seeing growing demand from customers across Europe and indeed around the world.
“We have a year of activity planned on the run up to our 20th birthday in November.”
Eurostar is offering passengers surprise upgrades from Standard class to Standard Premier class this week to mark the milestone.