Former Scotland centre Sean Lineen will be the English Championship club's director of rugby.
And Roddy Grant, who retired through injury after playing for Edinburgh, joins as a forwards coach.
SRU chief executive Mark Dodson said: "This is an exciting partnership which benefits both organisations."
Their most immediate goal will be to prevent London Scottish, who are third from bottom of the English Championship table, being relegated.
Dodson said the arrangement was the result of months of planning between two organisations that "share the common objective of developing and improving Scottish rugby".
"It provides a new, competitive step on the performance pathway for both players and coaches and we look forward to working with London Scottish CEO Rod Lynch and his team," he said in a statement.
Players sent on loan from Pro12 clubs Edinburgh and Glasgow Warriors, along with Scottish rugby academy and national age-grade players, will be based at the Richmond Athletic Ground and will be available to London Scottish for Championship and B&I Cup fixtures.
London Scottish chairman Sir David Reid said: "We will benefit from having experienced players, while we can provide the level of on-field competition that younger Scottish players need to aid their development.
"London Scottish intends to remain a successful and ambitious Championship club. Sean Lineen and Roddy Grant will help us achieve this.
"The relationship between the union and London Scottish has never been stronger. I really appreciate the leadership and vision shown by Scottish Rugby in this exciting initiative and the support they have shown to London Scottish."
Former Glasgow Warriors coach Lineen will work part-time at Richmond to support London Scottish head coach Peter Richards while continuing as Scottish Rugby's head of international age-grade rugby.
The 54-year-old will have responsibility for support staff, facilities, match scheduling, pre-season preparation and player recruitment.
Grant, the 28-year-old who played for Scotland A, joins the coaching team for the remainder of the season.
Scotland back Rory Hughes is currently on loan with London Scottish, while Scottish Rugby Academy players Robbie Fergusson, George Horne and Jack Cosgrove have also been with the Championship club this season.
Scottish Rugby has entered a new partnership through which the governing body will supply players and coaches to London Scottish.