Bernat, 25, made 74 appearances at Valencia as left-back before joining Bayern Munich, where he went on to play 115 matches in all competitions, winning four consecutive Bundesliga titles with the German giant.
"I am very proud to be joining Paris Saint-Germain,” Juan Bernat said after signing his contract.
"After my debuts in Spain and my experience in Germany, I will discover a new country and, above all, a new club who have made a spectacular rise in recent years. Paris Saint-Germain are known throughout Europe, with world-class players, the magnificent Parc des Princes and very big ambitions. I am also looking forward to working under Thomas Tuchel, whose work in Germany was remarkable. I am truly excited to be taking the next step of my career with Paris."
Bernat also has international experience with Spain, earning seven caps with the senior national side having enjoyed UEFA Under-19 Euro glory in 2012.