London-listed Saga, which focuses on services for the over 50s including holidays and insurance, has hired MHP following a competitive pitch.
The MHP team will report to Saga director of corporate affairs Tim McCall, who moved to the firm two years ago having previously worked in a senior role at MHP.
The appointment comes as Saga looks to expand new products such as its financial advice offer, called Saga Investment Services. In June the group said its priorities included "the ongoing development of opportunities in emerging businesses".
MHP MD Tim Rowntree said: "The business is at a very interesting phase in its development and we are delighted that Saga has appointed MHP. Saga is a very well-known and highly respected brand and we are looking forward to working with the management team to help ensure that the business and its investment case are fully understood by its key audiences."