Hamill will step down as non-executive chairman on April 9 2008. He joined the business at the end of 2000 as non-executive director and was made chairman five months later in May 2001.
Hamill has weathered some tough storms during his time as chairman of Moss including a prolonged period of uncertainty following serial stake building by entrepreneurs Shami Ahmed and Kevin Stanford in the early 2000s as well as more recent speculation that Baugur could bid for the business. He was also in the hot seat at Moss when the supermarkets began encroaching on its core tailoring business with the introduction of value suits under £50.
Moss Bros chief executive Philip Mountford said: "We would like to thank Keith for his services, particularly during the period 2001-2002 when the company faced exceptional difficulties."
The company said an announcement about the appointment of a new non-executive chairman would be made in due course.