She will report to Will Swayne, the global president at Carat, and will be based in the London office.
Lloyd has been at Carat for ten years, joining as a business director. Before this she was an account director at Mindshare Worldwide between 1998 and 2005.
Swayne said: "[Fiona] knows our network intimately and has extensive global and local management experience. Fiona is passionate about our clients, our talent and embodies the values of our organisation.
"She is perfect for the role and will enable Carat to continue to redefine media for our clients around the globe."