Fireworks and flame-throwers greeted Benzema, wearing their black and yellow kit with the No. 9, at Al-Ittihad's 60,000-seat stadium in Jeddah, where a giant 'KB9' was emblazoned on the pitch in bright lights.
"Assalam o aleikum!" (Hello), the 35-year-old said to the crowd, before hoisting the Ballon d'Or -- the trophy he won last year -- above his head.
Benzema joins Portugal idol Cristiano Ronaldo as the latest superstar to join the Saudi Pro League, which has a hit-list of high-profile targets, according to a source close to the negotiations.
The Frenchman's appearance in Jeddah follows a strenuous Saudi courtship of Messi before the Argentina World Cup-winner opted for Inter Miami on Wednesday as his final club before retiring.
It also comes after Saudi-funded LIV Golf pulled off a shock merger with the PGA Tour and DP World Tour following more than a year of acrimony and legal disputes that divided the sport.
Benzema, who won five Champions Leagues, four La Liga titles and three Copas del Rey with Madrid, said he was hoping for more silverware with the Saudi champions.
"I'm hungry, I want to play and show what I can still do on the pitch, and especially to put the club where it should be, which is right at the top," he told a brief press conference.
With billions of dollars in oil wealth, Saudi Arabia has been on a buying spree of sports assets as part of plans to diversify its economy and attract tourism and investment.
The conservative monarchy, often targeted over its human rights record, bought English club Newcastle United in 2021, the same year it hosted its first Formula One Grand Prix.
'Je t'aime Benzema' In January, Ronaldo, 37, joined Riyadh club Al-Nassr in a two-and-a-half-year deal said to total more than 400 million euros. No figure has been released for Benzema.
The Public Investment Fund sovereign wealth vehicle that is behind the purchases also took controlling stakes in four clubs, including Al-Ittihad and Al-Nassr, this week.
Saudi Arabia, whose neighbor Qatar hosted the World Cup last year, is tipped to bid for the tournament after exploring a tri-continental edition with Egypt and Greece.
Supporters, many wearing Al-Ittihad colors, created a festive atmosphere at the unveiling, waving yellow flags and placards saying "Benzema 9" and "Je t'aime Benzema" (I love you, Benzema - in French).
A drone image of the player's face hovered above the venue in the Red Sea city, the gateway to the holy city of Mecca where Benzema, a Muslim, has performed two "umra" pilgrimages.
Banners welcoming Benzema adorned the city, and according to press reports, 60,000 tickets at the symbolic price of nine riyals ($2.50) sold out within five hours.
After joining Madrid in 2009 from Lyon, Benzema made 648 appearances and is second on Real's all-time goalscoring list with 354 -- only Ronaldo has more.
But after a stellar 2021-22 season when he led Real to Champions League glory and was rewarded with the Ballon d'Or, he was troubled by injuries in 2022-23 and missed France's World Cup campaign in Qatar.
© Agence France-Presse