The 33-year-old has signed a three-year deal at the Parc des Princes after PSG triggered an £8.5m release clause in his Aston Villa contract, though several French outlets have placed the figure closer to €10m.
Digne first came through at PSG between 2013 and 2015, making 30 appearances before he was sold to Barcelona, and he went on to spend time at Everton before joining Villa in a £25m deal from the Merseyside club in January 2022.
His return ends an eight-year stint in England, during which he made 182 appearances for Villa and established himself as one of the most reliable full-backs in the Premier League.
"I am very honoured to be returning to Paris Saint-Germain following the wonderful experience I had here more than ten years ago," Digne said.
"I am particularly impressed by how the club has developed over the years."
The left-back is expected to serve as competition for first-choice option Nuno Mendes under head coach Luis Enrique, rather than a guaranteed starter, joining a PSG squad that has won back-to-back Champions League titles, the most recent of those coming via a penalty shootout victory over Arsenal in the 2026 final.
Digne had been a regular for France throughout their run at this summer's World Cup, starting on the left of defence as Les Bleus kept three consecutive clean sheets against Sweden, Paraguay and Morocco in the knockout rounds.
Digne leaves Villa Park having been part of the side that won the Europa League last season, ending the club's 30-year wait for a major trophy since 1996. His exit is the third among Aston Villa's senior squad this summer, after playmaker Morgan Rogers joined Chelsea and midfielder Youri Tielemans moved to Manchester United, with Unai Emery's side having lost significant experience from last season's title-winning squad in a short space of time.
Villa will have limited time to adjust to life without Digne, given PSG are due to face Emery's side in the UEFA Super Cup on 12 August, meaning the defender could line up against his former club within days of completing his move to Paris.