The 39-year-old former back-row forward, who has most recently been working for sports agency Red Sky Management, played for ScotLand 77 times and captained the team on 19 occasions.
He toured with the British and Irish Lions in 2005 to New Zealand and his career included spells with Glasgow Warriors, Sale Sharks and French side Clermont Auvergne.
White has a sports science degree and is looking forward to embarking on a new career as a trainee PE teacher.
Meanwhile, current BT Sport Academy member and Melrose player George Taylor, who left Loretto in 2015, has joined up with the school and will coach twice weekly.
And David Guy, who has represented Scotland at hockey and is now a coach, has joined the hockey coaching group at the school.