None of the big pre-favorites won the most prestigious award.
Instead, the choice fell on the French director Julia Ducournau's bold horror drama "Titane".
The film has been described as a nightmare-like mix of comedy, sex, violence, psychedelic lighting and throbbing music.
The role of chairman of the Cannes jury has this year been shouldered by Spike Lee and for the first time it has consisted of more female than male members, including actress Maggie Gyllenhaal, director Jessica Hauser and singer Mylene Farmer.
But when the heavy prizes were to be awarded at the closing ceremony, it did not go quite as planned.
Instead of reading out the winner of the award for best actor, Lee instead happened to reveal who was awarded the Palme d'Or.
Norwegian received an award
The award for best female actress went to Norwegian Renate Reinsve for her role in Joachim Trier's "The World's Worst Man".
In the side category Un certain regard, where more innovative works compete, Kira Kovalenko's Russian drama "Razzhimaya Kulaki" ("Unclenching the Fists") won first prize.
The jury's prize is awarded to Sebastian Meise's "Grosse Freiheit" ("Great Freedom").
Last year, the Cannes Film Festival was canceled due to the corona and a Palme d'Or - a prize that is considered one of the biggest in the film world - was never awarded.
Therefore, the interest in this year's film gala in the French resort has been all the greater and both critics and journalists have reported on a high quality of the star-studded event.
Many standing ovations
Several heavy prestige dramas, such as Ryusuke Hamaguchi's "Drive my car", Asghar Farhadi's "Ghahreman" ("A hero") and Mia Hansen-Løve's relationship drama "Bergman island" have premiered.
But also lesbian nuns (Paul Verhoeven's "Benedetta"), bedridden porn stars (Sean Baker's "Red Rocket") and a light-metal splatter horror (Julia Ducournau's "Titane") have been on the program.
Standing ovations have been a constant feature in the reporting from the festival. According to industry press, Sean Penn's "Flag day" was four minutes long, Celine Dion's biography "Aline" was honored with five minutes and Wes Anderson's journalist comedy "The french dispatch" - which was to premiere at last year's festival - enjoyed a nine-minute standing ovation.