The 'Come & Get It' hitmaker's mother Mandy Cornett and her husband Brian Teefey have welcomed a baby daughter.
Demi Lovato sent a shout out via Twitter to Gomez following the arrival of her sibling, reported Aceshowbiz.
"Selena Gomez is a big sister. Everyone congratulate her and her famil," she wrote.
Gomez's parents divorced when she was five years old. Her mother Mandy married Brian in 2006. The couple expected their first child together in 2011, but she suffered miscarriage and lost the baby girl named Scarlett.
"Hope all the amazing moms had a great day! I have the best momma in the world. I love you so much!" she wrote.
The 20-year-old singer is currently working on her new masterpiece "Stars Dance".