He assumes the role effective Jan. 1, following the departure of Magna Global Exec VP Todd Gordon, who left last month to help TubeMogul build out its programmatic TV capabilities.
Mediabrands, the media agency network within Interpublic Group of Cos., houses media agencies UM, Initiative and BPN, as well as central specialist groups like Magna Global and barter operation Orion.
Mr. Cohen's appointment follows a leadership change earlier this year in which Henry Tajer succeeded Matt Seiler as global CEO of Mediabrands. Mr. Tajer was global chief operating officer at Mediabrands, based in Sydney and has since relocated to New York.
"David's rise to oversee Magna Global U.S. is the natural next step for a leader that has already so positively impacted our clients and network with his forward-thinking strategies and solutions," said Mediabrands CEO Henry Tajer in a statement. "He's now rightly positioned to bring even greater innovation across Magna's core capabilities, working hand-in-hand with his partners at UM, Initiative, BPN, Cadreon and our other speciality units."
Mr. Cohen is a 17-year-veteran of IPG. He established UM's digital practice in 2001 and a decade later was named global chief investment officer of UM. He was behind Mediabrands' "nine-figure-deal" with Facebook, and serves on the 4A's media leadership committee.