Florence ran Europe from New York over the past two years, but Draftfcb decided to relocate the role to London, with Orlov joining on September 4.
Laurence Boschetto, worldwide president and chief operating officer, said: "We owe David our deep appreciation for the many contributions he has made to establishing Draftfcb in Europe and the Middle East over the past two years, while helping to make it profitable -- and to Draft for 18 years before that."
Draftfcb has hired Orlov two months after it emerged he and EMEA president and chief executive were leaving Wunderman without jobs to go to after a restructure.
Orlov joined Wunderman in 2000 and rose to worldwide vice chairman and chief executive of global automotive operations, which involved managing relationships across 40 countries for Ford, Jaguar, Land Rover, Lincoln, Mercury, Volvo, Mazda and Rolls-Royce.
Earlier in his career he ran a strategic communications agency and was marketing director of Volvo UK for three years.
Boschetto said: "Alexei is well-suited for his new role. Over the past 25 years, he has established a clear track record for reinventing agencies and for resuscitating brands."
Draftfcb London handles Vauxhall's UK direct marketing account and Draftfcb Milan also has the General Motors Opel marque as a client.