The announcement comes just two years after Forrest sold the agency she founded, Forrest International, to the Golin/Harris network.
She will hand over a 100-strong team to Rosemary Sayer, former regional head of corporate affairs for Standard Chartered Bank.
Forrest will remain as a consultant to the Asia network, taking on the role of non-executive chairman.
As MD she was responsible for activity in Singapore, Hong Kong, Taiwan and Tokyo.
Golin worldwide director of marketing and branding strategies Ellen Ryan Mardiks said: 'Anne has contributed a great deal not just in terms of the Hong Kong office, but across the entire region. She has been crucial in expanding Golin/Harris's corporate and financial PR to include a marketing capability.'
Golin/Harris now boasts an Asia-Pacific client list including The McDonald's Corporation, Samsung and Texas Instruments.
Sayer, who will join the group in early February, returns to Golin/Harris after a two-year stint in-house at Standard Chartered Bank developing corporate comms across Hong Kong, China and north-east Asia.
She formerly worked as deputy managing director of Forrest International where she specialised in corporate affairs, crisis management and executive training.