Celebrities eager to celebrate the 70th anniversary of the festival walked the red carpet for the opening ceremony.
They included Bella Hadid, Kirsten Dunst, Uma Thurman and Julianne Moore.
Drama Ismael's Ghosts, starring Marion Cotillard, was the first film to have its premiere at the Palais, the heart of the action during the 11-day event.
Jessica Chastain, on the jury deciding the key award winners, hugged Thelma and Louise actress Susan Sarandon on the red carpet, while British Oscar nominee Naomie Harris was there for the first main event of a packed festival.
If you're not one of the thousands of industry professionals, budding actors or media in town for the festival, here's what you might have missed from its opening scenes.
Among the stars who turned heads and set the paparazzi bulbs flashing included Julianne Moore and Susan Sarandon, Bella Hadid (and her plunging neckline) and Elle Fanning.
It's fair to say Will Smith is pretty chuffed at being on the Cannes jury alongside the likes of Paolo Sorrentino - even though he said seeing three films a day was something he'd not done since he was a teenager.
He almost bounced into the jury press conference, giving a whoop before seeing his name badge set on the desk and announcing he would be "playing the part of Will Smith today", then jokingly called security on a photographer getting a little too close.
The Fresh Prince of Bel Air star joked he would wear 32 outfits during the festival, after he was told previous juror Kirsten Dunst had worn 28 during her stint. But he conceded that it was too hot in the resort to be sexy and that being comfortable was key.
"I started off wanting to be sexy - really south of France Cannes sexy, but that really went out of the window today," he said.
There was no word on his thoughts on jury president Pedro Almodovar's maroon tracksuit and shades that he wore for the press conference.
Being chosen as the opening film of Cannes may be a coup for the crew and cast - but that doesn't save it from being critically mauled.
Ismael's Ghosts, directed by Arnaud Desplechin, is about a woman returning to her film director husband after being missing for 20 years, but finding him with a new lover. It was described as "time-wasting" and "self indulgent" by The Guardian.
While The Hollywood Reporter is a little kinder, it says the film "won't be an easy sell".
But it clearly left a nasty taste in Variety's critic Peter Debruge's mouth, as he wrote: "If Ismael's Ghosts were a meal, it would be a massive slab of off-tasting meat alternative, wrapped in fake bacon, cooked in margarine, then covered in dairy-free imitation cheese."
The reviews for Loveless, which was also screened on Wednesday, were much better. Matt Anderson of BBC Culture described it as "brilliant - but heavy and relentlessly grim".
He said: "After his last film, Leviathan, the director Andrei Zvyagintsev came in for a lot of criticism in Russia for the dark picture of the country he put forward. Loveless is in many ways even harsher and more direct in its condemnation of daily life under Putin.
"It played very well at the press screening - but it will be interesting to compare the reactions from Russia and abroad."
Those lucky enough to have accreditation for the festival could have been forgiven by being confused when they picked up their pass.
For this year, as a tongue-in-cheek addition, badges with a variety of well-worn Cannes phrases came attached to the lanyard.
Guests were seen discussing who had the best slogan, with phrases - in French and English, and chosen by the Cannes team - including "I'm so pathetic I took a selfie on the red carpet", "Who won the Palme d'Or last year?" and "How come I didn't get invited?".
That last one has already been heard at least once on the Croisette, Cannes' strip of hotels and beaches hosting lavish parties, even though the festival has barely begun.
Speaking of uninvited guests, one of the stars of the upcoming Emoji Movie - the one featuring Sir Patrick Stewart as a bow tie-wearing piece of poo - crashed into Cannes as the festival was getting going.
T J Miller parasailed onto a pier outside the Carlton Hotel in the heart of the town, only to promptly fall in the water. Soaking wet, he declared he thought it was "funny" - so no sad face needed here.
The publicity stunt came despite - or perhaps because of - the fact the film is not being shown at Cannes.
The Cannes Film Festival runs until 28 May
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It may have only been the first day of the Cannes Film Festival, but it was packed with glamour as stars descended on the sunshine-soaked resort.