Fairfax Media can reveal Olympian Cusack has signed a one-year deal with the Brumbies to chase his childhood dreams after a three-year stint in the Australian sevens program.

Cusack's arrival comes as versatile back Robbie Coleman prepares to leave the capital after securing a release from the final year of his contract to join the Western Force.

The Brumbies deal caps a whirlwind year for Cusack, which started with a broken wrist before being named in the Rio Olympic Games sevens team of the tournament and finishing with a rugby homecoming.

But the 23-year-old said his heart always belonged to the Brumbies and Super Rugby as he started his mission to chase a drought-breaking title.

"I'm pretty chuffed. Being born in Canberra you dream of playing for the Brumbies," Cusack said.

"I'm happy with the path I've chosen, I've done everything there is to do on the sevens circuit and now it's time to give 15-a-side a crack.

"Sevens has definitely made me a better player. It isolates skill assets and it's easily transferable, I think it's only enhanced my game."

Cusack will play for NSW Country against the Perth Spirit in the National Rugby Championship grand final on Saturday, linking with future Brumbies teammate Kyle Godwin in the championship match.

Cusack wants to turn his 12-month Brumbies audition into a long-term future as he attempts to force his way into a back row already boasting Scott Fardy, Jordan Smiler, Jarrad Butler, Chris Alcock, Lolo Fakaosilea and Tom Staniforth.

The Brumbies have two roster spots to fill for the 2017 campaign, with coach Stephen Larkham set to search the globe for a potential playmaker recruit.

Coleman has joined the Force in an unexpected move while Christian Lealiifano is fighting a battle against leukaemia and Matt Toomua has moved to England.

Cusack will offer a point of difference in the back-row battle as a 102-kilogram hard-nosed ball-runner and a 191-centimetre lineout jumper.

Larkham offered Cusack a deal at the end of 2015 in a bid to lure him to Super Rugby.

But Cusack had his heart set on playing for Australia at the Olympics and stuck by his ambition despite a wrist injury almost shattering his hopes.

Cusack missed four months of the Olympic build-up, but managed to earn a spot in the sevens squad for the Games.

"You do have a fear of letting one door close [to Super Rugby] and opening that one of the Olympics," Cusack said.

"You wonder if you'll get the chance to open it again with the sliding doors. But I was comfortable knowing that at the time in my career I was happy to go down the Olympic path.

"If the Brumbies opportunity came up in the future I would have jumped at it, but if it didn't I was prepared to live with that."

Brumbies players started their off-season holidays on Friday, with the squad to resume pre-season training in mid-November.

Larkham will tour Europe as a Wallabies assistant coach before rejoining the Brumbies in December.

"It's been a pretty good. At the start of the year when I had a broken wrist, to think that I would have achieved all this is something I don't take for granted," Cusack said.

"I'm blessed that the coaches have faith in me. It will take some time to adapt but I believe I can do that and I'm looking forward to it."