Fast Retailing, Japan's largest clothing chain operator, will ask executives in offices both at home and around the world to conduct meetings and write documents in English.
Staff will be requested to obtain at least 700 points in the Test of English for International Communication, a globally recognised benchmark in language ability by March 2012.
Store managers and other staff will also face undergoing English Communication Training as part of the company's new language strategy.
Announcing the new policy, Tadashi Yanai, president and chairman of Fast Retailing said: "This move is necessary for a Japanese company to survive as a global corporation," according to this article in the UK newspaper The Telegraph.
The switch from Japanese to English is in line with Fast Retailing's rapid global expansion plans, which aim to make the company the world's biggest fashion retailer by 2020.