The German, who has been out of work since leaving Borussia Dortmund last summer, will succeed Unai Emery at the Ligue 1 champions.
A post from the club’s official Twitter page confirmed the appointment of Tuchel and said he has signed a two-year contract in Paris.
The tweet said: “Paris Saint-Germain are delighted to announce that Thomas Tuchel will be the new first-team coach next season.
“The German tactician has signed a two-year contract with the French champions.”
The 44-year-old, who had previously been linked with the Arsenal job, said he was proud to join the club.
“It is with great joy, pride and ambition that I join this great world football club that is Paris Saint-Germain,” Tuchel said on the club’s website.
“There is extraordinary potential in Paris and this is the most exciting challenge that I have received.
“I am also looking forward to experiencing the Parc des Princes, a legendary European football stadium with a fantastic atmosphere.”
Tuchel joins the club having previously led Dortmund to the DFB-Pokal Cup in 2017 before he left the Bundesliga side.
Emery, whose contract expires at the end of the current season, joined PSG from Sevilla in 2016.
He has led the club to two Coupe de France and two Coupe de la Ligue titles as well as the Ligue 1 championship this season.