JWT won the business after a pitch, understood to have been against DDB. The activity will run across press, online and media partnerships, including linking up with a social networking site. The campaign breaks in October.
WWF already works with a number of blue-chip companies, including Marks & Spencer, HSBC and Nokia, on their environmental efforts.
Paul Kirkley, JWT's business development director, said: "Sustainability is becoming even more important to big businesses today. Consumers are far more selective about which brands they buy into and take into account companies' attitudes to the environment. This brief hits at the heart of these challenges and we are really looking forward to working with WWF."
Last year, WWF appointed Kitcatt Nohr Alexander Shaw to its DM account. DDB previously worked on ad briefs for WWF on a project basis.