The London Borough of Southwark and Westminster City Council will now work together on comms, policy and public affairs. The two comms teams will remain based at their respective councils, with key areas of mutual focus including public health and jobs for younger people.
Although the move is thought to be partly prompted by budgetary pressures, PRWeek understands there are no job losses expected this year.
The roles of Alex Aiken, director of comms for Westminster City Council, and Southwark Council's head of comms Robin Campbell, will also be unaffected.
Leader of Southwark Council Peter John said: 'We need to work closely together in the best interests of central London, the economic powerhouse of the UK. Whether it is the delivery of our big regeneration schemes or support for business, our common goal is to create employment in the heart of the capital, particularly for the young.
'That's why it makes sense to join our comms teams together to engage effectively in the important debates that central London must win.'
The joint venture will focus on five core comms areas, including residents' surveys and data analysis, and policy research.