Rees will oversee all commercial and operational aspects of the DCM business, which, following the addition of the Vue cinemas contract at the end of last year, now accounts for around 80 per cent of the cinema ad sales market.
Since leaving his role as the chief executive of Mindshare in 2002, Rees has worked with a number of companies, including the now-defunct digital outdoor media owner Avanti Screenmedia as its chief executive.
Rees joined Mindshare as its managing director in 1998 from TMD Carat, where he was the deputy managing director, and was promoted to chief executive in 2001 before resigning a year later.
DCM is jointly owned by the Odeon and Cineworld cinema chains. Crispin Lilly, the vice-president of business affairs at Cineworld Cinemas, stepped in to support the management team following the departure of Bowley.
Lilly said: "I am delighted that Simon is joining the team. His background and commercial experience will further strengthen DCM's position as UK leader for strategic planning and implementation of all forms of cinema media."
In addition to the ad sales for the Odeon, Cineworld and Vue cinema chains, DCM has contracts with Picturehouse, IMax and other independent cinemas.