The new in-house agency follows similar moves by Westminster City Council and Essex County Council. Both have already launched commercial agencies in competition with the private sector.
Brighton & Hove's new agency will focus on providing 'shared service solutions' to public bodies, making communications more efficient.
Its first client is the CIPR Local Public Services Group, which will use it to promote an annual conference.
Brighton & Hove head of comms John Shewell said: 'Public services are facing a tough challenge - to improve services but with decreasing resources. Therefore, one of the big issues facing public services is doing more with less and communications is no different. This is why Brighton and Hove City Council has set up an agency to help public service comms teams manage their organisations' reputations.'
In April, Essex County Council launched Essex Communications to sell PR services to public bodies and private companies.
The council's head of comms Giles Roca subsequently left to go to Westminster City Council last week.