Gibson will have a seat on the group board and take over the day-to-day responsibility for all of Seven's client business, building client satisfaction and the continued growth of its multi-platform offering.
Gibson joined Seven from Redwood in 2010. Before then she spent three years at Haymarket as publisher of women's glossy Eve, having spent the previous 13 years at the BBC.
The promotion follows a raft of new appointments within the agency, including Will Watt as business development director, Emma Martin as group account director and Dave Buck as financial controller.
They join Brand Republic's former group publishing director, Rachael Stilwell, who will head up Seven's rapidly expanding business to business division.
Sean King, chief executive officer at Seven, said: "There has never been a more exciting time for Seven as brands increasingly recognise the power and value of content to deliver to the bottom line, so the timing to promote Jessica to MD is perfect.
"Her extensive experience in newsstand publishing and working with major blue chip clients mean she has exactly the right skills to drive Seven’s client business forward.
"It also allows me to focus on developing new opportunities for the business as we continue to grow in the UK and internationally."
Gibson said she was excited about the company's ambitious plans to further develop the "power and value" of clients' owned and earned media.
Seven's clients include Sainsbury's, English Heritage and Lloyds Banking Group.