He joins the backroom team this week as the squad prepares for the pre-season fixture at Plymouth Albion on Saturday.
Warriors Director of Rugby Mike Ruddock said: "We are delighted to announce that Brian is joining the club in the capacity of Director of Sports Medicine. He brings with him a wealth of experience from working in an Australian sporting environment as well as in rugby with Cornish Pirates, Connacht and Ospreys.
"Brian has gained a masters degree in physiotherapy and as such brings impressive skills and experience that add huge value to the club. His experience will ultimately benefit the other members of the physiotherapy department as well as the players themselves."
Downey studied his masters in Manipulative Physiotherapy in Australia before moving back to his homeland Ireland to work for Connacht.
And the 44-year-old revealed the challenge of helping Warriors move up the Guinness Premiership was a huge attraction.
"I'm very excited about the position and joining Warriors. It's nice to be involved with a club that is clearly moving forward with a real commitment to getting into the top half of the Guinness Premiership," said Downey.
"I'm looking forward to working with the coaching set-up and in the Guinness Premiership. Mike Ruddock, Clive Griffiths and Billy McGinty have impressed me as have the entire backroom team."