Arnold has been heading Profero's UK operation for seven years, and is also the chairman of IPA Digital. The appointment comes into effect on 1 April.
He is to be replaced as the managing director by Nick Blunden, who has been the client services director at Profero since September 2004.
Daryl Arnold will remain as the chief executive of Profero, and Daniele Fiandaca as the group chief operating officer.
Blunden previously worked as an e-business consultant for IBM and as the marketing manager of the technology company Energist.
Wayne Arnold said: "For me to step away from the position of managing director of the UK business, I needed to find someone who would actually do a better job than me, and in Nick, I am confident that we have found exactly that."
Profero, which has offices in London, Madrid, Milan, Munich and Paris, hopes to develop its European presence in the same way it has in Asia.
This week, it revealed it had bought the Chinese agency Blue Flying Fish. It is the first Western agency to take 100 per cent ownership of a local agency, which it is allowed to run without a Chinese partner.
Profero has also teamed up with the UK post-production company Golden Square to set up Profero Goldensq, which will provide high-quality moving-image advertising for the internet.