Curzon, who joined the Suffolk brewer in 2004, will leave at the end of March.
Adnams managing director, Andy Wood credited Curzon with the successful development of new products such as Explorer, Yuletide and Spindrift.
He also praised him for his central role in building the company’s social and environmental reputation and his work on the Beer from the Coast campaign.
“He has been a great ambassador for this business and it is with our very best wishes that Steve moves on from Adnams, leaving us well prepared for future growth,” said Wood.
Wood will look after the brand while a decision is made on his replacement. It has not yet been announced where Curzon will go to.