Pastore announced the deal Tuesday on his blog without giving any financial details. French reports say the transfer will cost PSG about ?43 million ($61.1 million), surpassing the ?33.5 million ($47.6 million) PSG paid Real Madrid for striker Nicolas Anelka in 2000.
Pastore said he still has to undergo a medical test and finalize some details but ''you can officially say that I'll be a Paris Saint Germain player.''
PSG has yet to confirm the deal, but Palermo president Maurizio Zamparini said on French radio station RMC's website that a deal has been agreed with PSG's sporting director, Leonardo.
''Yes, we have reached an agreement with Leonardo and PSG,'' Zamparini said. ''The negotiations are over. Pastore is a PSG player. I think he will be unveiled in Paris sometime between now and Friday.''
The 22-year-old Pastore scored 11 goals for Palermo in Serie A last season.
''I'm very excited to begin this new stage (of my career). They explained the project and I was immediately seduced by the challenge,'' Pastore said. ''PSG is a great club with a great history.''
PSG is financially backed by majority shareholder Qatar Sports Investments and has already signed several other players for the new season.
Leonardo, who quit as Inter Milan coach to join PSG last month, recently bought Italy goalkeeper Salvatore Sirigu from Palermo.
PSG last won the French title in 1994 and last played in the Champions League seven years ago.
''I want the team to win everything,'' Pastore said. ''I'll give my best in every match. I'm very happy they have faith in me.''