Dentsu Aegis Network will handle planning and buying, PPC, programmatic and data transformation remit across the UK, France, US and Canada. It strengthens the current relationship with the business as 360i handles SEO services.
The review follows a four-month review and Dentsu Aegis Network will begin working on the new business in August.
The pitch process was handled by ID Comms and involved agencies from GroupM and Omnicom in earlier stages of the process. The incumbents Arena Media and DigitasLBi also took part in the process.
Lionel Benbassat, the head of marketing and brand at Eurostar, said: "Over the next three years, Eurostar is going through a significant transformation with the aim to deliver a more personalised experience for future and existing customers.
"With iProspect/360i we have found a partner with the right balance of innovation, commercial rigour and customer orientation to support us in our journey towards being Europe’s most loved travel experience.
"It was a very competitive pitch process and the quality of work demonstrated by competing agencies was of a very high standard.
"I would personally like to thank our incumbent agencies – Arena Media for their commitment and considerable contribution to our business over the last five years, and DigitasLBi for their expertise and support."
Eurostar’s upcoming projects will include Autumn campaigns and promoting its new fleet of trains.
Chris Whitelaw, the UK chief executive at iProspect, said: "We were incredibly excited to have the opportunity to respond to such an interesting brief and deploy the best of Dentsu Aegis Network’s talent, tools and technology throughout this innovative and comprehensive process.
"The prospect of working with a brand as cherished as Eurostar, combined with the digitally-led agenda with performance right at the centre has energised and galvanised our entire organisation, and we can’t wait to get started."