The project - currently under the working title Natural Vision - is planned to involve a £90m first phase, including a domed ecosystem.
Following a competitive pitch process, the agency has been charged with developing a commercial strategy for how potential brand partnerships of Chester Zoo and Natural Vision can be maximised, and to secure long-term commercial partners.
Gavin Peters, account director at Havas Sport and Entertainment's Insight division, said: ‘The Natural Vision project will be one of the most important animal conservation projects undertaken anywhere in the world in the next 20 years. We are thrilled to have been selected to work with them.'
The domed ecosystem will be an African rainforest-themed sanctuary for a wide variety of wildlife including gorillas. Other developments include a 90-bed ‘wildlife' hotel, a conservation college, and a marina development.