Sampdoria's Reto Ziegler (Photo: Reuters)
Juve, who finished seventh in Serie A for the second successive season and failed to qualify for Europe, have already signed Italy midfielder Andrea Pirlo from AC Milan.
Former Tottenham Hotspur player Ziegler has penned a deal until 2015. Juve had problems at left back last term with Paolo De Ceglie injured for much of the season and Fabio Grosso frozen out.
The club sacked coach Luigi Del Neri last week and are poised to appoint former midfielder Antonio Conte in his place.