He will report to Chris Tanner, chief executive of the mortgage and protection networks.
Graves is to develop potential new business opportunities, provide strategic support to the management team and use his experience to enhance the existing proposition.
He recently left his role of managing director at Sesame Network and PMS Mortgage Club.
Graves said: “The opportunity to join a business with a clear and unambiguous goal of becoming the best home for mortgage and protection advisers was too good to miss.
“HLP and MSN benefit from being one of the few network groups in settled private ownership, which allows us to concentrate on building upon the existing strong foundations to deliver a world class proposition that benefits our members and every product and service partner equally.
Shaun Almond is managing director across both networks.
Graves added: “I shall also be using my experience to help build the proposition that Shaun Almond and his colleagues need to generate even greater volumes of new business from our current firms while making the proposition irresistible to other mortgage and protection firms across the UK.”
Tanner said: “We are delighted to have Mark on board. His experience of the network sector allied to the connections he has throughout the mortgage market are going to be key components in our drive to establish the group’s proposition as the most attractive in the market.
“We are putting together a team which will be able to support our growth plans and Mark Graves will play a major role in helping us achieve those goals.”