The 25-year-old musician, who suffers with Lupus, took to Instagram where she said she had to go through the procedure for her overall health.
"I'm very aware some of my fans had noticed I was laying low for part of the summer and questioning why I wasn't promoting my new music, which I was extremely proud of. So I found out I needed to get a kidney transplant due to my Lupus and was recovering. It was what I needed to do for my overall health," Gomez wrote.
The "Hands To Myself" hitmaker further thanked the team of doctors and her friend Francia Raisa for donating her kidney to Gomez.
The singer went to call on people to spread awareness about Lupus.
Gomez also said she would soon talk about her journey through these past several months in the run-up to her surgery.
She was diagnosed with the autoimmune disease in October 2015.