Pringle, 41, replaces the departing Steve Lawrie and will be joined by new assistant coach Nikki Walker at Myreside ahead of the new competition which starts after the Rugby World Cup later this year.
Since playing professionally for Edinburgh Rugby and Scotland A Pringle has held coaching posts with Boroughmuir, Currie and Romania under-20 and, most recently, has been working as a rugby development officer in East Lothian.
He said: “I am delighted to be given the opportunity of being the head coach of Watsonians.
“They are a club that I have always admired with strong traditions and Stevie has done a great job in the last two seasons to get them competing for play off places.
“I’m looking forward to working with Nikki, the support staff and the players in the new Super6 format but also with the rest of the teams across the club to build on the success of the whole of Watsonians.”
Walker, 37, earned 24 Scotland caps on the wing and the former Hawick head coach has been a member of the Scotland under-20 coaching set-up over the last two seasons.