Los Angeles, California - Olivia Rodrigo rang in her 21st birthday at a lavish bash complete with famous faces and some seriously stellar style.

The singer turned 21 on Tuesday, but with the GUTS World Tour on the horizon, she got her celebrations rolling early with a weekend birthday bash.

On Monday, Olivia wowed fans with snaps from her party shared via Instagram, where she poked fun at her excitement to start drinking – legally, that is.

"today is my last day of being able to underage drinking (hypothetically) !!!!" she wrote under the post.

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The IG photos revealed her bold glam for the celebrations, rocking a dark red lip and her hair in a chic updo with a daring halter-top black dress.

Further photos showed Olivia celebrating with some of her closest friends, including Madison Hu, Tate McRae, and Iris Apatow.

Also featured was fellow singer Conan Gray, who appropriately commented, "her first drink ever!!!"

The Heather artist led Tuesday's tributes to the birthday girl, sharing some adorable new photos with Olivia in honor of her big day.

"twenty one years of the best girl ever," Conan captured his post, which began with a sweet snap of the long-time BFFs sharing a hug.

The slideshow included plenty of memories between the pair, including a recent trip to Disneyland with Madison and Iris.

While Olivia's rumored boyfriend, Louis Partridge, was not featured in any of her birthday snaps, he was spotted with her on that very trip to the most magical place on Earth, so it seems the two are still going strong.

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The Grammy winner hasn't shared any photos of Louis on her socials just yet, but she's dropped plenty of not-so-subtle hints, including a darts scoreboard bearing both of their initials for the players.

Following the star-studded celebrations, Olivia is heading back to work as she kicks off the GUTS World Tour in Palm Springs on Thursday.