Rileys wants to promote the clubs on a local level making them leisure venues for the communities.
CMG will work with the clubs individually, focusing on regional press coverage.
The chain wants to attract a broader range of customers than just die-hard pool fans. It will position the halls as places people can come to eat, drink and socialise as well as play pool.
It wants to compete against independent pool and snooker halls, cinema, bowling alleys and general leisure venues.
It has been previously reported that the smoking ban has affected trading conditions for the company.
CMG will build local awareness of the clubs and encourage footfall. It won the account following a three-way pitch.
Rileys currently has 162 sites nationwide. Last July former parent company Georgica sold the snooker and pool hall arm to a private equity consortium for £35m.