The three-year award for the international corporate services company follows an extensive bidding process. It will involve a phased approach to delivery.
The first phase covers 11 NATO entities across five markets, with successful delivery serving as a stepping stone to securing business for a second phase with an additional 13 markets.
Mike Holmes, worldwide government services director for HRG, said: "This contract marks a true milestone in the way NATO has procured and managed travel services and all of us in HRG are truly delighted to be able to make today’s announcement. The tender process was extremely professional and thorough, enabling HRG to demonstrate its expertise and position as a world-leading provider of corporate services to deliver the optimal service for NATO.
"NATO has high expectations and has set us challenging targets which we are looking forward to achieving. HRG looks forward to providing NATO with an efficient and cost effective travel service that meets their specialist needs, while achieving savings and adding value across their entire travel programme."
NATO used events agency M for the recent NATO Summit at Celtic Manor Resort, Newport.