The appointment is the first to be made by the agency's new chief executive, Jed Glanvill, since taking over in October.
Murphy is currently responsible for running MindShare's Unilever account.
She joined MindShare in 2000 from Carat following stints working at MediaVest and Initiative. She was promoted to the agency's executive management team in 2004.
Martin Rees, another former managing partner, has also been promoted to become the managing director of MindShare's House of Media, its non-traditional media department. A new emphasis will be placed on this department, putting it at the centre of the agency.
Rees will be briefed to develop existing divisions within House of Media as well as to develop new areas. Existing divisions include MindShare Interaction, the agency's digital offering.
Other promotions include Rosie Faulkner, who sits on the MindShare executive team, to planning director.
Andy Zonfrillo, another member of the agency's executive team, has been promoted to head of investment, taking over from Nick Theakstone, who recently moved to a Group M role.
Zonfrillo will oversee media buying across traditional media, and reports to Glanvill.
Glanvill said: "We have a strong management team at MindShare. It's an endorsement of our strength that we can promote from within."