During his 11 years at MindShare, Simon rose to president, chief strategist, overseeing strategic operations of MindShare North America.
Alan Cohen, U.S. CEO, said while trying to meet "the needs of a difficult economy and complicated media landscape, it has become apparent that this new role is ... essential."
OMD said Simon will focus on developing innovative ways to help clients "launch and relaunch brands," while helping the agency "define reinvented media."
Simon, who joined MindShare in 1998, began his career in media planning at Young & Rubicam, while also working later at Grey, Avrett Free & Ginsberg and Campbell Media Alliance (a TN Media unit).
OMD also represents Visa, Nissan and Intel.