Dwan, who has spent more than three decades with the Magners manufacturer and became FD in 1999, steps down in May. His responsibilities will pass to recently appointed chief operating officer Stephen Glancey.
The news comes after C&C in November installed high-profile former Scottish & Newcastle boss John Dunsmore as its new chief executive, taking over from Maurice Pratt. Glancey is a former colleague of Dunsmore at S&N, as is new C&C strategy director Kenny Neison.
Dwan joined the group in 1975, becoming chief financial officer in 1980.