The supermarket chain will start supplying the cross-Channel rail service with sandwiches, ready meals, salads and drinks from Tuesday, also marking its first big move into northern Europe.
The employee-owned grocer, part of the John Lewis Partnership, will supply all standard-class buffet cars across the entire Eurostar fleet with hot and cold food, including mushroom risotto, chicken tikka masala, classic British sandwiches and croque monsieur grilled cheese and ham sandwiches.
It marks another major expansion abroad for the chain, which already earns export sales of £25 million a year - up 20% over the past year. Waitrose already supplies food to 45 countries including Singapore, Thailand, New Zealand and India.
David Morton, Waitrose business-to-business director, said: "This is a very exciting opportunity for us to work with such a prestigious brand, which shares our commitment to quality and service.
"To be the first food brand that Eurostar's customers experience when they are visiting Britain is tremendously powerful as we seek to expand our presence within northern Europe."
Julian Welham, head of on-board services at Eurostar, said: "Our British passengers will be well acquainted with the Waitrose brand, but for many of our continental customers this will be their first experience and we look forward to introducing them to the new range which includes both French and British classics."
Waitrose also has a smaller catering deal to supply yoghurt and fruit to premium passengers on British Airways flights.
The retailer has been a rare success story amid a squeezed grocery market in recent years, with its latest market share hitting a record 4.9%, according to market researcher Kantar Worldpanel. It has 291 shops across the UK and Channel Islands. No value or duration was placed on the deal.