Kesha says the party don't stop ... and, neither do her hottest pics -- 'cause we've got a whole bunch from her entire career to highlight her birthday!

The singer-songwriter turned 38 Saturday ... and, she's still baring all in her pics -- like in this one she posted where she got totally nude before going for a dip.

And, she's also willing to show ever inch of her bod in her professional life too ... getting on all-fours on the hood of a car in the music video for her song "Joyride" that came out just a few months ago.

And, while she's stuck to mostly blonde hair throughout her career, Kesha also went through a brunette phase ... a look she totally pulled off.

Like we mentioned, Kesha released "Joyride" last year ... and, her other single "Delusional" came out later in 2024 too. She's gearing up to release a full album later sometime in 2025.

The clock may tik-tok ... but, Kesha's clearly aging like a fine wine -- or a bottle of Jack Daniel's like she used to brush her teeth with!

Happy birthday!