Fisher will assume responsibility for the regulator’s consumer credit division with effect from 1 April in addition to his current responsibilities as director of Consumer Direct.
Watson meanwhile, will manage a new Pipeline and Performance Group within the Markets and Projects division.
Watson (pictured), who has been director of consumer credit at the OFT since 2008, will now oversee a department responsible for tracking delivery and the effective use of resources, intelligence gathering, supporting the development of new project proposals and assessing remedies.
The changes are accompanied by further management re-shuffling in other departments, which sees Clive Maxwell placed in charge of a newly combined Infrastructure, Public Markets and Services Group, Meanwhile Robert Laslett will lead a newly combined Consumer and Goods Group.
John Fingleton, chief executive of the OFT, said: "Today's changes mean we can use our resources more efficiently, reducing the numbers of management layers and reporting lines and increasing our accountability and transparency.
"In doing so, we will continue to focus on delivering work and decision making as effectively and consistently as possible."