The 42-year-old gave fans some of their most memorable moments, from winning the Irish Cup twice to beating Ole Gunnar Solskjaer’s Molde (with a certain Erling Haaland up front) at Mourneview Park, and recorded four third-placed Premiership finishes.
He ensured the Lurgan-based club finished in the top-seven in 10 of his 11 full campaigns in charge and helped numerous players secure moves across the water.
Here are some of the best moments of Hamilton’s tenure in pictures.
9. Glenavon celebrate third-placed Premiership finish
Glenavon finished third during the 2014/15 Premiership season behind champions Crusaders and Linfield to secure another European spot. Hamilton is pictured here celebrating a 3-2 victory over Portadown where Andy McGrory's late penalty helped the 10-man Lurgan Blues take a step closer on April 18, 2015 Photo: Tony Hendron/Presseye
10. Boxing Day drama
Another Boxing Day victory over Portadown in dramatic circumstances in December 2015. Rhys Marshall scored a last-gasp winner at Mourneview Park to seal a 1-0 win over their rivals. The Lurgan Blues would finish third in the table once again - a feat Hamilton achieved four times during his almost 12-year reign Photo: Tony Hendron/Presseye
11. Back in another Irish Cup final
Gary Hamilton celebrates with Kevin Braniff after the forward scored four goals in their 4-3 2015/16 Irish Cup semi-final victory over Crusaders at Windsor Park Photo: Kevin Scott / Presseye
12. Moment to remember
Glenavon repeated their Irish Cup success in 2015/16 as they defeated Linfield 2-0 thanks to goals from Kevin Braniff and Andy Hall. Here's Hamilton celebrating with his children and the trophy at Windsor Park Photo: Brian Little/Presseye