In his new role, Nazerali will lead strategy, insight and thought leadership across Carat globally, reporting into Doug Ray, president of Carat Global.
He brings a background as a market researcher and advertising planner, and senior experience in strategy and insight.
Before the BBC, he worked on the original team that developed the New Labour brand, worked at MTV Europe as senior vice president, marketing, chaired the Viacom Europe Marketing Council, and launched VH-1 in the UK and MTV in India and Taiwan.
Ray said: "Carat's ambitions to redefine media are taking us into pioneering territory, and helping clients reinvent the way that brands are built.
"Sanjay is a recognised leader and expert in insight and strategy, a broad and creative thinker – at once practical and surprising. We're delighted he has chosen to join us, he will be a massive contributor to our future success".
Carat Global is part of the Dentsu AegisNetwork.