Johnson, who has held the posts of Assistant Coach with Australia and Head Coach of USA since leaving Wales in 2006, will initially spend time operating in an observational capacity at the region, ahead of formally assuming full responsibility as Director of Coaching.
Speaking about the challenge that lies ahead, Johnson said: "Returning to Wales is going to be something of a homecoming for me and I can't wait to work again with players and coaches I know well from my time with the Welsh team, as well as the exciting young talent that is coming through the ranks at the Region.
"The Ospreys have been a real success story in recent years and I'm looking forward to working with the coaching team to help build on that success. The Region has a great attitude, some outstanding players and a focus on development of home grown talent that was one of the key factors in making the decision to move. I certainly want to help the Ospreys reach their full potential wherever I can and refining the team's rugby performance and development programme is going to be a career defining experience for me. The challenges are clear and so are the goals.
"With a side that has already achieved so much - Magners League Winners, EDF Cup Winners and reaching the final stages of the European Cup - the task is even more focused, even more challenging and the expectation even greater, particularly at a time when recent results have been disappointing. But this is a perfect opportunity to help develop and enhance the Ospreys' pitch presence and game-play. It's a task that means working on different levels throughout the organisation, helping deliver a stream of subtle improvements combined with innovation that, when taken together, can make a big impact. It's this type of thinking that I'm looking forward to exploring, working alongside the existing coaching team to deliver on the strong ambition that I know both supporters and management have for the Region."
Mike Cuddy, Ospreys Managing Director, added: "We are delighted to welcome Scott to the region as our new Director of Coaching. He brings with him a reputation as an exciting, innovative and visionary rugby brain, who we're sure will hit the ground running.
"The search for a Director of Coaching has been a lengthy one, but we're in no doubt that in Scott we have found an individual with the qualities we need to see us make a giant stride forward on the pitch.
"It has long been our stated desire to see the Ospreys firmly established amongst the leading sides in European rugby, a goal Scott shares with us. He has a passion for Wales, and for Welsh rugby, and has vast knowledge not only of domestic rugby but wide ranging international experience at the very top level.
"Our recent performance has been extremely disappointing, we have underachieved and failed to live up to our potential. Scott's arrival is extremely timely. We had previously identified where the organisation needed to be strengthened and his appointment is a part of a much wider plan aimed at re-establishing and enhancing the Ospreys' on-pitch performance. The entire organisation is totally focused on the task ahead and the need to deliver the type of performance and results that supporters of our Region deserve."