The move follows the promotion of Stuart Smith to global CEO last year.
Ogilvy has expanded in the past four years, adding South Africa, Kenya and the Middle East and North Africa to its network.
Frohlich joined Ogilvy in 2012 as UK MD and MD of the EMEA brand marketing practice. Before this he was a board director at Bell Pottinger for eight years.
Frohlich told PRWeek: "I will be working on a long-term strategy and plan to build on the growth we already have in the EMEA region, focusing on marketing processes, HR and new business to keep up the momentum."
Smith said: "Michael has done an outstanding job in London, taking the agency from strength to strength using his own blend of style and creativity. His appointment reflects his contributions to our success in the UK, and marks a new phase in our growth strategy and a shift in our approach to running the region. With Michael’s help we will be able to accelerate our growth plans."