Katy Perry Shares Baby Face Throwback Photo to 21st Birthday to Celebrate 'Idol' Milestone

The pop star took it back to her 21st birthday.

Katy Perry is celebrating American Idol's 21st season with a sweet throwback picture.

The show's host shared a picture of herself on Instagram from her 21st birthday. It was taken in 2005, three years shy of Perry's breakout album, One of the Boys.

In the photo, a bare-faced Perry poses smiling with her hands on her hips, while sporting a beaded, tasseled white v-neck top.

"#idol is celebrating its 21st bday this year. When I turned 21 I rented a roller skating rink 🛼 and had McDonald’s “cater” along w/ 2 kegs in the middle of the rink… and two friends broke bones but we had a lot of fun (so I was told idk I had just turned 21 🤸🏻‍♀️🍹)," Perry wrote in the caption.

She also invited fans to watch American Idol, while asking fans to share their epic 21st birthday stories with her in the comments.

Perry recently made headlines for an emotional moment on the long-lasting singing competition.

In his audition, 21-year-old Trey Louis gave a touching rendition of "Stone" by Whiskey Myers. When he finished the song, he told the judges that he's a school shooting survivor. Louis shared that he was on American Idol because he wanted to bring some positivity to his hometown after such a heartbreaking tragedy.

Perry broke down in tears. "Our country has f—ing failed us! This is not OK! You should be singing here because you love music. Not because you had to go through that f—ng bull—t. You didn't have to lose eight friends," she said.