Holberry joined Magners GB as managing director in March 2008, after a seven-year stint as Coors' managing director of sales operations.
He said: “I have enjoyed working in C&C and building the Magners GB team over the last year. However the appointment of the new management team, headed by John Dunsmore, reduces the opportunities for me to develop my career.
"I will be working with John over the coming months to ensure a successful transition and wish him and all the C&C team every success in the future.”
Dunsmore, the former chief executive of Scottish & Newcastle, took the helm at C&C in November last year, and has brought in other members of S&N's senior management team, including Stephen Glancey as chief operating officer and Kenny Neison as strategy director.
He said: “We would like to thank John for his significant contribution to Magners GB since his appointment. We are delighted that he will work with us to ensure a smooth transition to the new management structure and offer him our best wishes for the future.”
Holberry is to leave C&C in August.