The agency pitched for the business against its sister WPP shops Ogilvy & Mather and Grey London after the holding company scooped the global ad account from McCann Erickson in June.
The WPP agencies Mindshare and OgilvyOne already handle IHG’s global media and CRM respectively.
Mike Greenup, IHG’s vice-president, marketing, Europe, said: "We’re very pleased that, in JWT, we have found a great partner to help us build our brands in Europe."
Joseph Petyan, the executive partner at JWT, added: "InterContinental Hotels has ambitious growth plans in Europe. We are delighted to be their creative partner and hugely excited by the challenge ahead."
IHG is the largest hotel chain in the world with brands including Holiday Inn, InterContinental, Express by Holiday Inn and Crown Plaza.