The former All Blacks lock has spent more than two decades with the team as a player or in a coaching role.
Otago is home. But he will move to Perth after the NPC to take up a two-year contract as an assistant with the Western Force.
"I think I signed my first contract with Otago at the end of 1999, so it’s been close to 25 years of a close connection or relationship with Otago," Donnelly said.
"It's been pretty emotional, I suppose. But it hasn't really sunk in yet. I've got a pretty big job to do yet, which I'm pretty focused on finishing."
That "pretty big job" is leading Otago to victory over Canterbury in Dunedin tomorrow.
"I want to do really well with Otago and when that comes to an end, I guess I’ll reflect on that. But I’ll be forever grateful for them giving me a crack as a player and a crack as a coach.
"I’ve only ever really coached in this region with Otago or the Highlanders, but the opportunity came up to keep coaching at Super Rugby level in a different part of the world, which is pretty exciting,"
That excitement is also tempered by the reality of the move.
He is settled. His wife, Jacque, and children, Harvey, 11, Charlie, 8, and Felix, 4, are settled.
They have a lifestyle block 20 minutes north of Dunedin.
"I think the family will probably stay here. I'll just go by myself for a bit first and just see.
"I've got three kids that are all pretty settled in school, and my oldest boy told me he wasn't that keen to leave.
"It's going to be a bit challenging for a start, but like any new adventure, things are a bit challenging to start until you figure out what works and go from there."
Figuring out what works against Canterbury is the more immediate challenge, though.
Donnelly has named a settled side for the derby.
Front-rowers Rohan Wingham and Henry Bell shuffle to the bench to make room for Green Island loosehead Ben Lopas and veteran hooker Liam Coltman.
Prop Abraham Pole missed the game against Taranaki for personal reasons but returns this week and replaces Moana Takataka on the bench.
Hudson Creighton and Josh Whaanga switch roles. Creighton will start at centre and Whaanga at wing.
Loose forward Lui Naeata drops out of the squad. He has a broken thumb and will be out for a couple of weeks.
His spot goes to midfielder Josh Timu, who was injured in the opening game against Southland.
Fullback Finn Hurley and lock Fabian Holland limped off in the first half against Taranaki but have been named in the starting XV.
Canterbury were humbled 46-21 by Wellington in their last outing, but they beat Otago 47-0 in the preseason and have named a team featuring plenty of talent.
Veteran prop Joe Moody and Highlanders flanker Billy Harmon will ensure the pack is more than competitive, and they have plenty of experience on the bench in the form of Ryan Crotty, Tom Christie and Daniel Lienert-Brown.
NPC
The teams
Otago: Finn Hurley, Josh Whaanga, Hudson Creighton, Thomas Umaga-Jensen, Jona Nareki, Cameron Millar, James Arscott, Christian Lio-Willie (captain), Harry Taylor, Oliver Haig, Fabian Holland, Sam Fischli, Saula Ma’u, Liam Coltman, Ben Lopas. Reserves: Henry Bell, Abraham Pole, Rohan Wingham, Will Stodart, Will Tucker, Nathan Hastie, Kyan Rangitutia, Josh Timu.
Canterbury: Isaac Hutchinson, Chay Fihaki, Dallas McLeod, Jone Rova, Ngatungane Punivai, James White, Tyson Belworthy, Torian Barnes, Billy Harmon (captain), Cullen Grace, Zach Gallagher, Jamie Hannah, Joe Moody, Ben Funnell, Finlay Brewis. Reserves: Brodie McAlister, Daniel Lienert-Brown, Gus Brown, Liam Jack, Tom Christie, Nic Shearer, Shun Miyake, Ryan Crotty.
