The 29-year-old has cost Al Nassr £23m and joins the likes of Cristiano Ronaldo, Sadio Mane, Marcelo Brozovic and Otavio at his new club.
Laporte departs the Etihad Stadium after five-and-a-half years, having joined from Athletic Bilbao in January 2018.
He made 180 appearances in total for Manchester City and notably headed in the only goal of the game in the 2021 League Cup final against Tottenham Hotspurs.
The France-born Spain international leaves Manchester City with five Premier League titles, two FA Cups, three League Cups, the UEFA Champions League and UEFA Super Cup.
Manchester City's Director of Football Txiki Begiristain paid tribute to Laporte, saying: “Aymeric has been an excellent player for Manchester City during a great time for the Club.
“He fit into the team seamlessly upon arrival in 2018 and played a key role in many of our successes over the years that have followed.
“The form of the other defenders in the squad made it hard for him to find sufficient game time in 2022/23 and we respect his decision to seek a move elsewhere.
“I look forward to following his career from afar.”
