Robbie Coleman was released from the final year of his contract with Brumbies to sign with Western Force in Super Rugby.
Coleman signed a two-year deal with Force, after making 80 Super Rugby appearances with the ACT outfit.
The 26-year-old utility back said it was a tough move to make.
"This is definitely the hardest decision I've had to make in my career," Coleman said.
"Being a Queanbeyan junior, it was always my dream to play for the Brumbies and I'm very thankful that I've been able to run out and represent the side 80 times.
"I'll miss Canberra and the Brumbies fans and thank them for all of their support over my years with the club."
Force head coach David Wessels was delighted with the signing, praising Coleman's versatility.
"Robbie has played 80 Super Rugby games in a successful team and has a winning mentality, but he's still only 26 years old, so he has a lot of good rugby left in him," he said.
"He can play a number of different positions in the backline which is useful for us and he's also a left footer which makes him very valuable.
"Most of all the thing I love about Robbie is that he's a winner. He's a very competitive guy and he is exactly the type positive energy we need in our group."
Force won just two of 15 Super Rugby games last season, while Brumbies were eliminated in the quarter-finals.