The Georgian has signed for PSG after passing his medical on Friday.
Rumours had been circulating for several days that the now ex-Napoli man would be joining the French giants.
Khvicha Kvaratskhelia has signed a contract until June 2029.
The announcement was made on the Spanish page of the PSG website. Napoli also published a press release confirming the transfer.
"Kvara had previously played for Napoli since 2022. In Italy, he scored 107 goals for the Partenopei and won the Scudetto in 2023," PSG's statement read.
"The current Serie A leaders will be paid €70m including bonuses."
"It's a dream to be here, I've heard so many positive things about PSG. I feel immense pride in joining this great club, and I can't wait to wear my new colours," the 23-year-old told the French club's website.
PSG chairman Nasser Al-Khelaïfi said he was "delighted to welcome Khvicha to the PSG family."
"He is one of the most exciting players in world football, a fantastic talent, but also a player who has courage and fights for the team above all else.
"He was so determined to be part of our great club, I know he will achieve all his goals with us."