The 22-year-old is back at the Italian giants after two seasons spent on loan at Vaduz in the Swiss league.
The full-back is now hoping to cement a place in the Juve line-up, though he faces stiff competition.
Born in Roodeport, Untersee is a Swiss junior international and was a key member of their Under-21 side.
He was identified by Juventus in 2011 and joined their academy that year, but has yet to wear the famous black and white stripes of the Turin club.
He has spent much of the time since playing for Vaduz and played in the UEFA Europa League last season.
Untersee has yet to be capped at senior international level by Switzerland and as such would be available for Bafana Bafana if there was interest from the national team selectors in his services.