Chapman became chief executive following the merger of Pioneer and Exeter Friendly societies in 2008.
Chapman said: “It has been an honour to lead The Exeter over the last 12 years.
“I am very proud of our people and their passion for creating a member-focussed organisation.
“We have a strong senior leadership team and board of directors who are driving the business in the right direction, so I feel now is a good time to retire and I look forward to seeing The Exeter continue its success.”
Wallace Dobbin, chairman at The Exeter, added: “Andy has made an outstanding contribution to the success of the Exeter.
“Through his determined, committed leadership we have gone from strength to strength and he leaves it with a clear plan for the future, a highly engaged and committed team and secure foundations for its continued development.
“He has made an indelible mark on this business and on behalf of the Board I want to thank him for everything he has done for this great organisation.”
He will be stepping down at the end of 2020.
