Verratti leaves PSG for Al Arabi in Qatar
Al Arabi posted a video on social media showing the midfielder in club colours.
Qatari-owned PSG released a statement thanking Verratti for his 11 years at the club.
Verratti "played a major role in our great history", said club president Nasser al-Khelaifi.
"Paris, the club and its supporters will always have a very special place in my heart. I will always be a Parisian," it quoted Verratti as saying.
Verratti, 30, has struggled with injuries. He also has a spotty disciplinary record, collecting 141 yellow cards and six reds for PSG.
Bans and injuries limited him to 29 Ligue 1 appearances last season, but that total was the most since he played 32 games in 2014-15.
New coach Luis Enrique had not selected Verratti this season.
PSG received no concrete offers from any of Europe's big clubs for Verratti, perhaps put off by his salary.
French media reported that the transfer that should bring PSG close to 50 million euros (53.7 million dollars).
Verratti won nine French league titles and the French Cup six times with PSG and the European Championship in 2021 with Italy.
After a summer in which the Saudi Arabian League continued to attract big-name players, including Verratti's former PSG team-mate Neymar who joined Al Hilal in Riyadh, the Italian is the second star to move to Qatar in less than a week.
Brazilian forward Philippe Coutinho joined Al Duhail on a season-long loan from Aston Villa on Friday.