Senegal s Gueye returns to Everton as PSG offload outcasts. PSG Twitter Site
Gueye, 32, signed for Everton for an undisclosed fee and has penned a two-year contract to June 2024, the Premier League side said.
French media reports said PSG could expect to receive a fee in the region of 10 million euros ($9.9m).
"Paris Saint-Germain would like to wish Idrissa Gueye the very best for the future," PSG said in a statement on their website.
Gueye previously spent three years at Everton before moving to PSG in 2019 for a reported £30 million ($34.6m).
The former Lille and Aston Villa player notably won two Ligue 1 titles in Paris, and also featured on their run to the Champions League final in 2020.
Gueye made 34 appearances last season but was one of several PSG players frozen out since the appointment of Christophe Galtier as coach in July.
PSG have been eager to reduce their wage bill to leave more room for new signings while also respecting UEFA's financial sustainability regulations.
Gueye's Senegal international teammate Abou Diallo, 26, has also left PSG, in his case to return to the Bundesliga to join RB Leipzig on loan.
The German club have an option to make the deal permanent at the end of the campaign.
Centre-back Diallo, who can also play as a left-back, joined PSG at the same time as Gueye in 2019, costing 32 million euros from Borussia Dortmund.
Also leaving PSG on Thursday was Layvin Kurzawa, with the left-back moving to the Premier League to join Fulham on loan until the end of the season.
Former Monaco star Kurzawa, 29, has won 13 caps for France but has not played for PSG since August last year.