The 28-year-old is one of seven Brumbies players departing the club following the end of the 2021 season.

He played his 50^th game for the club last month and was expected to pursue a bid for rugby sevens Tokyo Olympic selection following the conclusion of the Trans Tasman series.

Cusack made his debut for the Brumbies in early 2017 and went on to become the 18th captain of the side after he took on the role against the Queensland Reds in the Super Rugby AU final earlier this year.

The flanker is one of several player departures at the Brumbies, but 25 players remain contracted with the club next season.

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Brumbies' head coach Dan McKellar said it was always sad when players left the squad but it was the reality of professional sport.

"All of these players have contributed to the success and culture of the club over a number years with Tom in particular having a significant role as a leader within the group," he said.

"There's no doubt they'll all be missed by the organisation and we wish them all the best in their futures, as we have done personally to each of them as a team and organisation last week.

"At the same time, like last year, in challenging circumstances we have managed to retain a really strong component of the current squad moving forward which is exciting for the Brumbies and our supporters and we look forward to setting goals and achieving them in 2022."

Cusack joins departures including Mack Hansen, who is heading to Ireland, Harry Lloyd, who is off contract, and Issak Fines-Leleiwasa, Bayley Kuenzle, Reesjan Pasitoa and Reece Tapine who will make the move to the Western Force.