The pair depart Aegis as part of an ongoing management restructure instigated by the Aegis Group chief executive, Jerry Buhlmann.
Earlier this month, Simon Francis, the EMEA chief executive of Aegis Media, left the business.
Aegis, which has no plans to replace Rattle and Hunter, said that it intends to focus on creating stronger management at its networks, Carat and Vizeum, rather than at the Aegis Media level.
Stephen White, the Aegis Media global marketing and new-business director, is moving to the new role of global brand director at Vizeum.
Rattle and Hunter are both long-serving directors at Aegis. Rattle was appointed to the position of chief client officer in November 2008, having joined in 1995 as the client services director of Carat.
In his position, he was responsible for all international and global client teams in Carat and Vizeum, communications strategy, research, insight and global investment management.
Previously, Rattle had worked in various roles at ITV companies.
Hunter joined Vizeum as the chief strategy officer in 2003 after leaving the brand consultancy Red Spider.