After last month’s World Cup review, Robinson asked the Scottish Rugby Union to fund an extra coach who he said should be “a sage-like figure who can really add to what we’re doing.”
Johnson is an ex-Australian under-21 stand-off and centre, has been an assistant coach with both Wales and Australia.
He had a brief spell as caretaker coach of Wales and was head coach of the USA Eagles before taking on his current role as director of coaching with Welsh club Ospreys in 2009.
He will remain in Swansea until the end of the season and join up with Scotland for the June tour to Australia, Fiji and Samoa. Johnson has agreed a four-year contract with the SRU on a salary believed to be around £200,000 a year. As “senior assistant coach” Johnson will rank above attack coach Gregor Townsend and defence specialist Graham Steadman.
He will also fulfil the new roles of working with the professional team coaches and travelling widely to identify Scottish-qualified players.
Robinson, who was on the opposite side to Johnson when England played Wales and the British and Irish Lions faced the Wallabies in 2001, said: “I am delighted Scott has agreed to join the Scotland coaching team. I have huge respect for him as a coach and a person having coached against him on numerous occasions.”
SRU chief executive Mark Dodson added: “This is a significant appointment for Scottish Rugby. In addition to working with Andy and the national management team, we are finalising an important wider role for Scott in helping us to better identify Scottish-qualified talent around the world.”
Johnson said: “I’m excited by this challenge. Scotland has a great history in rugby and with Andy there’s a real focus point to get it back to where it belongs on the world stage by creating something new and brighter.”