The 'C'Mon' singer had been receiving treatment for an eating disorder, but announced her departure on Twitter on Friday (7 March).
In a series of positive tweets, 27-year-old Ke$ha explained she was "happy and healthy" after two months in the facility, which she checked herself into voluntarily.
She wrote: "Happy to be back! Feeling healthy & working on tons of new music. I can't thank my fans enough for all the love & support u have given me.
"Life is beautiful. I'm so blessed to have u all."
As well as dropping the dollar sign from her Twitter name and changing it to her birth name Kesha Rose, she also posted a snap of herself with vibrant pink hair.
Alongside the photograph where she can be seen wearing a 'survivor' T-shirt, she wrote the message: "Had to go play in the sand."
While receiving treatment, Ke$ha kept her fans updated by asking a friend to tweet on her behalf.
She wrote in January: "Hey It's Kesha from treatment. I just wanted to say that this is really hard and necessary work. I'm grateful for all the love and support.
"THANK YOU. SOOO MUCH. I'm overwhelmed to tears by all of the love, letters, and support!! I'll be back soon and better than ever."
Ke$ha entered rehab early this year to "learn to love herself again" as she battled an eating disorder.
The 'Tik Tok' singer issued a statement to her fans saying she'll be away for a while facing her demons.
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Watch the video for Ke$ha's single 'Crazy Kids' ft. will.i.am: