The news comes five months after Gunn announced his plans for retirement in July earlier this year.
Friends’ chairman Sir Adrian Montague thanked Gunn for his years at the life office and “for staying on longer than he had originally planned”.
Montague said: “I thank Ben on behalf of the Board for his contribution over many years of productive service and success with Friends Provident. He has done a tremendous job recently easing the transition for Trevor Matthews into his role as chief executive officer. I am very grateful to Ben for staying on longer than he had originally planned and I wish him well for an enjoyable and well earned retirement.”