Fowler succeeds Marco Rimini, who has moved into the newly-created role of chief development officer, reporting to global chief executive Nick Emery.
As chief executive of Mindshare Worldwide Central she will now be responsible for running the agency's global client teams and also reports to Emery.
Mindshare has also created Rimini’s new role to allow him to "drive core differentiating products", such as Shop+, its bespoke service for brands on Amazon, and the agency’s global Fast initiative (Future Adaptive Specialist Team).
Rimini, who joined the agency 11 years ago from J Walter Thompson, has been tasked with working with regional Mindshare chief executives and global client leaders to support them so the agency can better become "adaptive marketing partners" that clients want.
Fowler has been replaced as global client leader for Team Unilever by Ailsa Lochrie, who was EMEA chief operating officer.
Lochrie will now be responsible for WPP’s second biggest client account. Last month Unilever announced its marketing budget was likely up be up year on year after a decline in spend last year, the analyst Liberum reported.
As EMEA chief operating officer, Lochrie was working in a coordination role alongside Helen McRae, the Western Europe chair who is also UK chief executive. Lochrie’s replacement has not yet been chosen.