Lizzo looked like a dolled-up Barbie at the Los Angeles premiere of Paris Hilton's "Infinite Icon: A Visual Memoir" documentary Tuesday night ... showing off her dramatic weight loss in a skin-tight dress!

Check out the pics -- the singer is radiating confidence in a curve-hugging light pink mini dress paired with bedazzled heels. She elevated the pretty 'n pink look with a pair of sparkling hoop earrings that brightened up the pink carpet thanks to her half-up, half-down hairstyle.

Lizzo looked like she had a grand ol' time at the premiere ... watching the doc seated next to Paris herself with Demi Lovato on the other side. Other A-listers supporting the night's star included Heidi Klum, Carmen Electra, and more -- just check out our gall!

We caught Lizzo coming out of the Hollywood event, and she said the film was so good they were dancing in their seats. She even called Paris a popstar ... perhaps a potential collab in the works?

Lizzo shimmied into her tiny 'fit nearly 1 year after revealing she hit her weight goal ... and dropped 16% of her body fat. She had been open about her ongoing health and fitness journey ... and has been showing off the results like it's her job.

Congrats to Paris on one heck of a doc ... and to Lizzo for crushing her goals!