Blackwell UK chief executive Vince Gunn has left the retailer with immediate effect.
Andrew Hutchings, previously chief executive of Blackwell Book Services, has been promoted to the role.
Hutchings will now have full responsibility for both Blackwell Book Services and Blackwell UK.
Gunn has not revealed what he plans to do next.
Blackwell chairman Stephen Harlow said there are “significant synergies to be gained” from aligning the two businesses. “Hutchings’ appointment enables us to move quickly to a single executive management structure,” he added.
Hutchings joined the company as head of IT and marketing in 1987. He was appointed as UK managing director in March 2005 and then chief executive of Book Services in March last year.