The 21-year-old made the move from Arsenal on transfer deadline day and will shore up the left-back position.
"There aren't many differences between Juve and Arsenal. Juve have won more titles, but they are both big sides," he said in a Press conference.
"Juventus are a very, very important club. I decided to come here despite receiving other offers.
"The moment the idea of the Bianconeri was suggested, I immediately said I wanted to come here."