The former Barcelona academy player made a move to PSV on a five-year deal from PSG last year upon the expiry of his contract.
Simons left Spain to join the French capital in 2019 before making his professional debut in 2021 and winning the league and Coupe de France.
"Xavi Simons immediately leaves the training camp to complete the transfer with Paris St Germain," PSV said in a statement.
Simons helped PSV secure a second-place finish in the Dutch top flight, making 34 appearances, scoring 19 goals and registering eight assists.
He has won the KNVB Cup, Johan Cruyff Shield and Eredivisie's top scorer award during his time at the club.
"The attacker came to PSV last year and became an important player in Ruud van Nistelrooy's (former manager) team," the club added.
