Neymar has signed a two-year contract that sees PSG receive a transfer fee that is worth €90m.
The 31-year-old spent six seasons in the French capital and won five league titles but the closest he came to winning the Champions League with PSG was losing the 2020 final to Bayern Munich.
Neymar made 173 appearances for PSG and scored 118 goals during his time at the club, which was also marred by untimely injuries.
His last appearance for the French champions came in February when he sustained a season-ending ankle injury.
PSG president Nasser Al-Khelaifi said: "It is always difficult to say goodbye to an amazing player like Neymar, one of the best players in the world.
"I will never forget the day he arrived at Paris Saint-Germain and what he has contributed to our club and our project over the last six years.
"We have had great moments and Neymar will always be a big part of our history.
"I would like to thank Neymar and his family. We wish him all the very best for the future and his next adventure."
Some of Neymar's new teammates at Al Hilal include former Chelsea and Napoli defender Kalidou Koulibaly, Ruben Neves and Sergej Milinkovic-Savic.
"I've achieved a lot in Europe and enjoyed special times, but I have always wanted to be a global player and test myself with new challenges and opportunities in new places," Neymar said.
"I want to write new sporting history, and the Saudi Pro League has tremendous energy and quality players at the moment," Neymar added.
"I have heard a lot and learned that I am following a long list of Brazilian players who have played in Saudi Arabia over the years, so I believe it is the desired place."
