The 19-year-old France Under-19 international featured eight times for the Ligue 1 Champions since making his debut in February 2021.
Michut will now play his football in the Championship at the Stadium of Light after becoming Sunderland's eighth transfer this summer - and Mowbray's first - and the club have an option to make the transfer permanent.
Speaking to Sunderland's website, he said: "I had a fantastic experience at Paris St Germain, but now I'm ready for a new challenge and I'm very happy to be here.
"This is an opportunity for me to level up as a player and I always wanted to play in England, but I also like the project and that is why I'm here. My preparation for the season has been good and I'm ready to help the team."
Michut will be available for selection in Monday evening's league match versus rivals Middlesbrough at The Riverside Stadium.