Johnson turned down a coaching role with the Cardiff Blues last year
Scott Johnson has been confirmed as the Ospreys' new director of coaching at the Liberty Stadium.
The Australian will leave his current post as USA coach at the end of the season after serving a three-month notice period.
Sean Holley will continue as head coach, with Jonathan Humphreys remaining as his assistant.
The pair recently signed three-year contract extensions and will work under the former Wales caretaker coach.
"This has been a long process, one we said we wouldn't rush from the outset," said Ospreys elite performance director Andrew Hore.
Interview: Ospreys elite performance director Andrew Hore
"Our overriding priority has been about establishing a coaching structure that will benefit not only the Ospreys but the region as a whole.
"We have considered over 20 coaches with the potential to measure up to a list of firm criteria and believe Scott Johnson contains the right mixture of technical ability - particularly on the attacking side of the game - strong character, excellent communication skills, planning, management ability and innovation to help the Ospreys take the next step forward."
"Scott will help ensure that progress is made on and off the field, through the continued development of the existing coaching team to whom the Ospreys are firmly committed and who, we believe, have the ability to go from good to great Welsh coaches in their own right."
Johnson had been thought to want to continue to play a part with the USA, but it is understood that the Ospreys wanted someone full-time in the new role of director of coaching.
The Ospreys have had a long search for a new man to replace former head coach Lyn Jones - who departed in May - with several previous targets turning down the Liberty Stadium side.
Holley has been holding the reins since then and has guided the Ospreys to the top of the Magners League and the semi-final of the EDF Energy Cup.
But Ospreys director of rugby Hore had continued the search for a high-profile senior coach he believed the region needed.
Former Wales lock Gareth Llewellyn believes that Johnson, 46, is just the type of coach that the Ospreys need.
"I think it would be an extremely shrewd signing," Llewellyn previously told BBC Sport Wales.
"He understands the game and I know the players there who worked with him in the Welsh squad will be delighted to have him there."
SCOTT JOHNSON CAREER
Born: Sydney, 19-08-62
Player: Fly-half/centre, NSW & Australia U21
2001: Named Australia A assistant coach and NSW Waratahs assistant coach
2001-6: Wales skills coach
2006: Wales caretaker coach
2006-7: Australia attack coach
2008: USA Eagles coach
Johnson was skills coach with Wales under Steve Hansen and Mike Ruddock before leading Wales in three internationals in a caretaker role after Ruddock's shock departure in 2006.
He left to become Australia attack coach, but departed after their poor World Cup showing in 2007.
Johnson remains close friends with Cardiff Blues director of rugby Dai Young, leading to speculation last year that the Australian could take up a coaching role at the Arms Park.
Instead he took the Eagles head job last year and he has led them to one win from six matches.
Ospreys coach Holley said: "Both Jon and I are delighted to have our roles confirmed on a permanent basis and are excited about the prospect of working closely with such an innovative and forward thinking coach as Scott Johnson."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.