.
For the event in Cannes, Katy took to the stage with long wavy black hair, along with subtle, glowy makeup.
The California native wore an eye-catching silver gown, with a skintight corset leading into a voluminous, puffy full skirt.
Despite having been pulled away from performing due to American Idol, Katy looked very at home on stage, dancing and interacting with her crowd as she sang.
An insider exclusively spoke to The U.S. Sun, and revealed that Katy was paid millions for her performance at the event, which leads up to the real wedding in July.
"They have invited 800 guests who are currently on a space-themed cruise around Europe, with stops in Barcelona and Genoa. It will arrive in Cannes on Friday for the big bash, which will be at a £40million estate," the source divulged.
"The party itself will only last five hours but Katy will headline it, with a DJ also being flown in as part of the top-tier entertainment.
"Afterwards, guests will watch a huge fireworks display from a small armada of ships waiting in the Bay of Cannes.
“When they say there’s been no expense spared, they really mean it."
Katy Perry called out for 'disrespectful' move toward American Idol crowd during judge's final episodeTHE ONE THAT GOT AWAY
Katy's billionaire gig came just weeks after she left American Idol.
Katy announced that she would leave American Idol while on February 12, and departed the show at the end of Season 22 last month.
An insider claimed that Katy might have left to spend more time with her family, or even to welcome a second child with her fiancé Orlando Bloom, 47.
The couple already shares one daughter, Daisy Dove Bloom, 3.
Star-studded guest list for the 'biggest wedding of all time'
ASIA's richest man is throwing the "biggest wedding of all time
Mukesh Ambani has a net worth of $116 billion and reportedly paid Beyonce $6 million to perform a private concert for guests at his daughter's wedding in 2018.
Anant is set to marry Radhika Merchant in June - and the bills are only expected to go up.
Billionaire Mukesh, owner of Reliance Industries and Asia's richest man, is known for throwing lavish parties.
On the star-studded guest list at the pre-wedding bash included people ranging across Silicon Valley, Hollywood, and Washington DC.
Among the invitees are Bill Gates and his wife Melinda, Mark Zuckerburg, and Ivanka Trump.
Disney chief Robert Iger also joined the extravagant event, following a deal agreed last week between Reliance Industries and Walt Disney to merge their Indian media businesses.
Other guests being expected at the Ambani event include BlackRock co-founder Larry Fink, Alphabet chief executive Sundar Pichai and former Canadian PM Stephen Harper.
Bollywood stars Amitabh Bachchan and Shahrukh Khan, cricket icons Sachin Tendulkar and M.S. Dhoni, and industry titan Gautam Adani are also invited in a who's-who of India's super-rich elite.
"With both of them working so much on projects, time as a family is also very precious.
"She’s spoken about wanting more sleep and feeling a lot more emotional than usual this season," the insider shared.
They added that the couple might also want a "baby brother or sister" for Daisy.
WATCH THIS SPACE
Alongside her rumored family dreams, fans think Katy has dropped a major hint that new music is coming.
Last month, Katy made a subtle change on Instagram hinting at a new avenue.
The star changed her profile picture to a plain red background, with a metallic graphic of her initials on top.
On X, formerly known as Twitter, many of Katy's social media followers took it as a sign that she's focused on music once again.
"OH WE ARE SO READY! KP6 IS FINALLY COMING!" one person exclaimed.
"Out of all the releases we had she's about to have the best," said a second.