Nottage will leave Kingsholm before the start of next season to become chief executive of the Three Counties Agricultural Society in Malvern.
He has spent 13 seasons with Gloucester after previously heading up the Newcastle United Sporting Club, where he held responsibility for the football, rugby, ice hockey and basketball clubs.
Nottage said: "I never thought I would work at the club for such a long time. I guess it just got hold of me in a way that no other job has.
"I consider myself very fortunate, and I would like to thank everyone who I have worked with and all who have supported the club during my time."
Nottage has been asked to stay on as a non-executive director at Gloucester to ensure a smooth handover with the incoming managing director.