The Argentine is looking forward to once again linking up with the Uruguay striker, having spent a season playing alongside one another during their time at Palermo.
The pair played alongside one another at Palermo between 2009 and 2010, before Cavani moved on to Napoli and Pastore joined the Ligue 1 club.
But after PSG splashed out a reported 64 million euros on the Uruguay striker, the duo will get the opportunity to form their attack once again.
"I am very pleased with his arrival," Pastore told PSG TV. "He is a great player.
"He will greatly serve the squad. I'm really happy to have a player of this level in Paris."
Pastore made 44 appearances for les Parisiens last season, scoring seven goals in the process, while Cavani found the back of the net an astonishing 38 times in his 43 games for the Partenopei.