The former All Black has accepted a role as the forwards coach at the Super Rugby club.
The 42-year-old joins the Force after an eight-year stint at Otago.
He had three years as an assistant before taking over the top job in 2020.
He also spent the past two seasons as an assistant coach at the Highlanders.
His coaching resume includes leading the New Zealand under-20 side to the 2022 Oceania championship.
He will link up with the Force for their preseason once his Otago commitments conclude next month.
Donnelly is replacing Irishman Jimmy Duffy, who returned home at the end of the 2024 season.
He was "thrilled" to be taking on the role, Donnelly said in a statement.
"Obviously, the opportunity to keep coaching at Super Rugby level is exciting, but talking with the people at the club, like Goody [general manager of rugby Chris Goodman] and Crono [head coach Simon Cron], the ambition of the club really took me aback," he said.
"They want to be a really competitive club in Super Rugby and while they’re in the building phase, the foundations are now in place which is really exciting about where we can go."
Donnelly made 15 appearances for the All Blacks in 2009-10.
The Rotorua-born lock clocked 82 games for Otago and 65 for the Highlanders.
He also had stints with the Crusaders and Blues and played professionally in France for Montpellier and Bayonne.
"Obviously, I played professionally for a number of years and coached now for a while, so I’ve worked with a lot of good coaches and in a lot of different environments.
"All that experience I have I can now bring to the Force."
Goodman is delighted to secure Donnelly’s services.
"His skill set around lineout and scrums has been a real strength throughout his career and set him apart, as well as his delivery style and his experience as a player at the top level," Goodman said.
"He’s been with a Highlanders group with a similar age bracket to what we’ve got at the moment, so he relates to the players really well and knows the trajectory we’re on."
"He brings a hard-nosed approach to things. He’s pretty black and white which complements the coaching staff.
"His long-term aspirations as a coach aligns to our thinking as a club around succession and stability too. We’re thrilled to have him on board."
The Otago union has already advertised the NPC coaching position.
Former Otago player John Leslie has previously expressed interest in coaching Otago and shapes as a leading contender.
The 53-year-old coached Northland last season and enjoyed back-to-back success with Southern in the Dunedin premier grade in 2022 and 2023.
Otago assistant coach and high performance development manager Ryan Bambry is another strong candidate.
Former Otago coach Cory Brown has accepted a two-year contract as the Highlanders attack coach and may be interested in the role as well.
Donnelly doubled up as Highlanders assistant and Otago coach in the past two years.
