The AFL is searching for a new football operations boss after Steve Hocking quit his post to return to Geelong as a replacement for outgoing chief executive Brian Cook.
Hocking will finish up at the league on Thursday and start his new position with the Cats in October.
Andrew Dillon, the league's legal counsel, will take on Hocking's key AFL role in an interim capacity.
AFL chief executive Gillon McLachlan hopes to appoint a replacement for Hocking before the end of the season, with former North Melbourne coach and current league employee Brad Scott regarded as a potential candidate.
Hocking has helped steer the AFL and its clubs through the COVID-19 pandemic and associated financial crisis over the last 18 months.
But he has also been a polarising figure with AFL fans since taking over as football operations boss in 2017, with a series of significant changes to the game drawing a mixed response.
There was plenty of angst at the start of this season when the "stand" rule was introduced for players on the mark, while Hocking also implemented the medical substitute rule.
He presided over the ill-fated AFLX experiment and rated changing the holding-the-ball interpretation midway through the 2020 season as the most contentious decision he made.
"Once you've made it you have to see it through and steer it through," Hocking said..
"There's no doubt the fans don't like significant change, and for obvious reasons - they care about the game."
McLachlan said Hocking took on a "brutal" role within the AFL and left the game in a better place with rule changes that have made it "more spectacular".
"You can make decisions to open the game up, but you need to understand what the unintended consequences are," McLachlan said.
"The way Steve's stepped through that over the last four years with the research and the work that's been done with a number of moves to get to where we are this year, the football is in fantastic shape and I think it's a great credit to him."
Hocking played 199 games with Geelong, including two losing grand finals, and served in several administrative roles before moving to the AFL.
The 56-year-old takes over from the widely-respected Cook, who has been in charge at the Cats for the last 23 years.
"They don't come up very often, particularly the Geelong one," Hocking said of his new role.
"If I missed this opportunity I may not have got that opportunity again.
"I've clearly got a long-term relationship with (Geelong) as well - I started there as a 17-year-old back in 1983 and there's a lot of history there for me.
"I've been fortunate to be in this (AFL) role, I've thoroughly enjoyed it and I think the time is right to take this role up."
Over more than two decades, Cook has rebuilt Geelong's finances and overseen the redevelopment of GMHBA Stadium.
The long-time administrator has presided over one of the most successful periods in the club's history, which has yielded three premierships, and introduced the Cats' women's program.
"Under his leadership, Brian has transformed the Geelong Football Club," Cats president Craig Drummond said.
"Steve Hocking's deep football and commercial experience is the perfect combination for our next CEO."