Barrowman was formerly head of client services at independent agency i-level, and before, that was head of radio and mobile at Initiative.
He will report to global digital leader Norm Johnston and will "focus specifically on working with and supporting the company’s client teams and existing digital talent."During his time at i-level, Barrowman worked on brands including Orange, the COI, LoveFilm and Next.
In his new role, he will work closely with Hannah Evershed, head of search and digital direct response.
Barrowman said: "Mindshare is uniquely placed as a strategic business partner to help brands take advantage of new consumer trends and communication opportunities."
Johnston said: "We’re thrilled to have Jonathan on our team. He’s yet another example of our commitment to growing digital by bringing in new digital talent, as well as investing in our existing teams. Jonathan brings experience and leadership across all digital media whether paid, owned or earned."
Barrowman is the latest hiring at Mindshare from i-level. In August, the former managing director of i-level, Mark Creighton joined the Mindshare UK office as chief operating officer.