There was no media pitch, but IHG evaluated several agencies before ZenithOptimedia was appointed.
Allan Yip, IHG director, brand management, Asia-Pacific, said: "To stay ahead of the market, we need to constantly review and ensure that our agencies have the right resources and capabilities and, importantly, the flexibility to align to our business, which is constantly evolving, given the changing dynamics of the travel industry."
Yip said ZenithOptimedia's "robust presence in Asia-Pacific" was a major factor.
"Our sustained investment and growth throughout Asia-Pacific makes it imperative for us to partner an agency that is aligned with our business objectives of enhancing brand visibility and driving revenue to our hotels.
We believe that ZenithOptimedia can add value in supporting our hotels with its in-depth market reach and resources, in addition to proven capabilities and flexibility."
Last year, IHG added more than 19 hotels with more than 5,500 rooms in Asia-Pacific. Over the next three years, it has set its sights on growing in high-demand markets such as Greater China, India and Australia.
As of April this year, the group had 154 hotels with more than 40,000 rooms in over 22 countries in the region.
Yip said MEC had played a critical role in helping to lay the foundation and increase awareness across the region for IHG's key brands, namely, InterContinental, Crowne Plaza and Holiday Inn. In the next phase of brand building, IHG needed to ensure its brands were top-of-mind for travellers through the right medium and channel, he said.
ZenithOptimedia started working with IHG last month, overseeing and managing media planning and buying initiatives, with Zenith Singapore as the leading hub agency.
M&C Saatchi has the creative brief, while InterContinental Hong Kong has appointed Motiv8 as its creative agency, replacing Bates Hong Kong.