Michael Murphy & aims to provide a range of specialist services to consultancies and agencies, and follows Murphy leaving Grayling this summer.
Services will cover areas such as entering new markets, finding talent, accessing capital and expanding through acquisition.
The firm will also support businesses in other sectors that are experiencing rapid change, need to respond to particular challenges or are considering international or sector expansion.
Launching the firm, Murphy explained that the "&" represented a wide network of partners he would use to help clients.
He said: "The need for all businesses to become social and the growing complexity of stakeholder engagement is opening up new opportunities for marketing services firms. There have been more than 500 M& A deals globally in the sector in the past 12 months.
"As this consolidation continues, these firms are also being replaced by a wave of new start-ups. They need support to grow and prosper. Similarly, there are many companies in manufacturing and services which, to survive, need to move from the comfort zone of their home market, sector or existing channels and expand their businesses."