Stormtroopers lined the steps of the Grand Theatre Lumiere as director Ron Howard and members of his cast arrived for Tuesday's screening.
Out next week in the UK, it depicts the early days of space pirate Han Solo.
Alden Ehrenreich plays the character made famous by Harrison Ford in the original Star Wars trilogy and Star Wars: The Force Awakens.
The 28-year-old was joined at the premiere by British actresses Emilia Clarke, Thandie Newton and Phoebe Waller-Bridge, who appears in the film as a testy robot.
The Fleabag star was joined at the film's beach party by her partner, the director and playwright Martin McDonagh.
Tuesday's screening in Cannes followed the US premiere that took place in Hollywood last week.
Speaking on Tuesday, Howard said being at Cannes with the film was important as the Star Wars saga "speaks to the entire planet".
"I've always been a fan of the Star Wars movies but now I realize why we see them over and over again," he went on.