PSG announced they had parted company with Antero Henrique, who had been in the role since June 2017, earlier on Friday.
And the French club have moved quickly in revealing Henrique's replacement, confirming Leonardo – who left AC Milan in May – will take over.
It is Leonardo's second spell at PSG as sporting director, with the former Inter and Milan coach having taken the same role in 2011, before leaving in 2013 after receiving a ban, which was later overturned, following accusations he had pushed a referee at the end of a match.
"I am extremely excited to see Paris Saint-Germain again," Leonardo told PSG's official website.
"This club has counted so much in my football career and in my life simply. I really had great emotions here as a player in the 1990s and more recently as a sports director alongside our President, Nasser Al-Khelaifi, when I returned to the club in 2011.
"I'm coming back to Paris with great enthusiasm and energy to be part of new club for which I have a deep respect."
Leonardo spent just one season as Milan's sporting director, and – along with coach Gennaro Gattuso – left San Siro following the Rossoneri's failure to qualify for the Champions League.
Meanwhile, Henrique's final season at PSG saw the club cruise to the league title, but fail in the Champions League and Coupe de la Ligue, while they lost to Rennes on penalties in the Coupe de France final.
Henrique reportedly endured a difficult relationship with coach Thomas Tuchel, who was said to have been frustrated with the club's dealings in the transfer market.