Chauhan will assume control of agency brands that include TME, Wunderman, Showdiff, Rediffusion Public Relations and OAP-Touchpoint, as well as Rediffusion DYR.
Nanda shifts to chairman, and will oversee the Everest Brand Solutions and Sudler & Hennesey brands.
Nanda commented: "My journey with Rediffusion DYR began along with Ajit Balakrishnan in the year 1973 when we started the agency to show the world that there was much more to advertising than writing smart slogans and drawing pictures.
"I think we proved our point aptly, but now believe the time has come for me to step aside and hand over the reins to Mahesh, who has the passion, vision and drive to take the company to the next level."
Nanda shifts to chairman, and will oversee the Everest Brand Solutions and Sudler & Hennesey brands.
Nanda commented: "My journey with Rediffusion DYR began along with Ajit Balakrishnan in the year 1973 when we started the agency to show the world that there was much more to advertising than writing smart slogans and drawing pictures.
"I think we proved our point aptly, but now believe the time has come for me to step aside and hand over the reins to Mahesh, who has the passion, vision and drive to take the company to the next level."