Eurostar carried more than 10 million passengers last year, for the first time since it launched nearly two decades ago - but has reached the target 15 years behind schedule.
The Anglo-French rail operator was launched in 1994 with the aim of reaching 10 million passengers per year by 1998, but was thwarted by competition from budget airlines.
However, the achievement will boost the UK government's plan to sell its 40 per cent stake in the business next year, with French state rail company SNCF the favourite to buy the shareholding on top of its 55 per cent interest in the cross-Channel rail service. After initial success in the wake of its launch, which saw more than 150,000 passengers use the London- Paris-Brussels service over six weeks, Eurostar struggled to meet its growth targets.
As the 1998 benchmark passed, the 2005 London bombings and the credit crunch pushed the ambitious passenger target further away.
Moving the London terminal from Waterloo to the St Pancras international terminal in 2007 also failed to increase numbers beyond 10 million immediately.
Weather conditions also took their toll periodically and in late 2009, the business suffered a public relations disaster when almost 2,000 people were trapped in the Channel Tunnel overnight, after melting snow leaked into train engines.
Eurostar said on Monday that it hit the 10 million level, one year after annual numbers rose to 9.9 million, just missing the critical mark despite the twin boost of the London Olympics and Queen Elizabeth's Diamond Jubilee.
A recovery in the UK economy, along with a busy summer for leisure travel across its routes, have helped Eurostar to reach its target, the train operator 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.
Nick Mercer, commercial director for Eurostar, 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."
As well as a new winter ski service to the Swiss Alps, this summer saw the successful trial of Eurostar's Route du Soleil service direct to Provence, in the south of France. The route will be introduced permanently from next year.
Eurostar doubled its 2012 profits to £53 million (HK$678 million) and its profit margin outperforms British domestic operators at 6.5 per cent.
Germany's Deutsche Bahn is threatening to end Eurostar's monopoly by launching a London to Cologne and Frankfurt service.