The billionaire is renowned for throwing extravagant parties, and he went all out with a bash at the posh Dorchester Hotel in the U.K. capital ahead of his 30th birthday next month (Jul12).
The celebrity guestlist included Carey and Anderson, who chatted to the prince in a special VIP area of the hotel's bar.
The pair then mingled with former screen sirens Welch, Faye Dunaway and Stephanie Beacham, as well as actresses Lea Michele, Marisa Tomei and supermodel Jerry Hall.
Anderson ensured she stood out at the glitzy event by grabbing a microphone to wish the third-in-line to the Brunei throne a happy birthday, before presenting him with a wrapped gift.
Prince Azim is no stranger to throwing parties which attract A-listers - in 2009, Janet Jackson and Sophia Loren attended his 28th birthday celebrations.