MRM is an 18-strong PR consultancy launched in 2003, headed by director Andrew Appleyard and based in Covent Garden.
Hughes, who is involved with Conservative politics in north west London, left the FCA after more than four years in July following nearly four years as campaigns director for the Electoral Reform Society.
He told PRWeek MRM was in the process of signing up to the APPC, which he had been involved with while at another public affairs agency, Waterfront Partnership, earlier in his career.
"The APPC membership is the first thing I started when I joined," he said.
Appleyard described Hughes as "the standout candidate" to enhance MRM’s offering as a "regulatory insider with a comprehensive understanding of the political challenges the financial industry faces".
Sophie Robson, a consultant who has worked at MRM for just over a year, is working with Hughes in the public affairs venture.
Hughes’ roles for the Tories are fundraising for the Hampstead Conservative Association and chairing the board of the north west London area Conservative Associations.
He said: "It is vital that those involved in financial services engage in the political conversation ahead of the general election to make sure it is an informed debate."