Larkham will be the club's head coach, while Fisher has been appointed the Brumbies' director of rugby.
As head coach, Larkham will have greater input and involvement with the overall organisation of the team and play a bigger part in recruitment and weekly selections.
Fisher will control day-to-day rugby operations with elements like staffing, elite and academy program development, talent pathways and training structures.
The appointments come following the shock resignation of South African-born World Cup-winning coach Jake White in September, who left just over a month after taking the side to the Super Rugby final.
At the media conference to announce their appointments on Friday, Larkham was confident he and Fisher could keep the club's momentum going.
"Nothing is going to change in terms of how we run the team," Larkham said.
"Off the field, it's going to be the same. Laurie spoke to the forwards, I spoke to the backs, and Jake oversaw that process."
Larkham, Australia's greatest modern day five-eighth, will also have greater authority over the team's overall attacking philosophies.
But he indicated there would be plenty of room for Fisher's input across the park.
"There's robust discussions, and you put in your arguments to one another. It's whoever argues the best point really, comes away with it at the end," he said.
"We're fairly logical sort of men, so we come down and understand where the other person is coming from."
Fisher, who was Brumbies head coach from 2005-'08, said the key to making the partnership work would be communication.
"Whether it's a marriage, or whether it's a rugby program, if you're not talking about it, you're going to struggle," he said.
"It's like any system. No one person in any environment determines exactly how it's done."
Fisher said on top of his new duties, he'd continue to focus on the forwards, the breakdown and the tackle contest.
"We need to develop more locally bred Brumbies players. So I'm really keen to get my teeth into that area," he said.
Brumbies chief executive Andrew Fagan said an assistant coach would be appointed to assist Larkham and Fisher.
"Their primary responsibilities will be defence, but will support the program as required," he said.