The not-for-profit group handed the agency the new retained brief following a competitive pitch.
Forum for the Future works globally with business, government and other organisations to help solve sustainability challenges.
Forster will develop a communications campaign aimed at enhancing the organisation’s UK media profile following the growth of its recently established New York office and the expansion of its work across South East Asia and India.
Melissa Fife, senior consultant at Forster Communications, will be leading the work alongside Adam Stones, Laura Buller and Libby Wyman.
Fife added: "We want to make sure that awareness of Forum for the Future’s pioneering work goes beyond the sustainability press and reaches mainstream media channels. Forster is well known for using communications to bring about positive social change and it is great to be working with an organisation that shares this passion."
Forster will also be working to support the launch of The World We Made, a book written by Forum for the Future co-founder Jonathon Porritt.