Edwards has been NatMags' managing director for the past three-and-a-half years and will take on the new role in addition to his existing responsibilities.
The new position is designed to reflect Edwards' role within the recently expanded company. It will also make him the official representative in the UK for the Hearst Corporation (NatMags' parent company) .
Last year, NatMags created two joint ventures; NatMag-Rodale and ACP-NatMag. Edwards will represent Hearst's shareholdings in the two companies.
He will also continue to head NatMags.
Rita Lewis, the managing director of NatMag-Rodale, and Colin Morrison, the chief executive of ACP-NatMag, will both continue to run their respective divisions and report to the joint venture companies' boards.
Victor F Ganzi, the president and chief executive of The Hearst Corporation, said: "The National Magazine Company has grown tremendously over the past few years. This title is a reflection of the reality of what Duncan has been doing and is appropriate given the size and complexity of the business."
At the same time, Simon Horne, the group finance director, has been made the general manager. He will retain his existing responsibilities.
Edwards said: "Simon's importance in getting our business in shape to manage the growth of the last few years has been immense.
"This new job title more accurately describes Simon's significant role in managing the engine-room functions of the company."