The hotel chain owned by The Intercontinental Hotels Group (IHG) already works with Mindshare on its £80m media business and OgilvyOne on its global CRM business and a number of smaller WPP shops across the world.
It is unconfirmed which WPP agency will lead the creative account.
The appointment is part of WPP’s decision to develop dedicated advertising, media and marketing teams to service big global clients.
In 2010 McCann Erickson New York was appointed as the lead agency to the £60m global account.
The agency picked up the business following a pitch against Fallon in the US - the group's previous roster agency.
In March Holiday Inn launched a major new integrated campaign in support of its London 2012 sponsorship.
The campaign, created by McCann Manchester, includes a 30-second spot and featured four-times BMX World Champion and London 2012 medal hopeful Shanaze Reade.
Holiday Inn is the official hotel provider to the London 2012 Olympic and Paralympic Games.