The 'Wolves' hitmaker is believed to have jetted out of Los Angeles on Wednesday afternoon (26.12.17) on a private with her girl pals, and they are planning on soaking up the winter sun at a hotel by the ocean.
A source told E! News: "She seemed very excited when she landed and was giggling with her friends and taking photos.
"They are all planning to do some fun dinners and spend New Year's Eve together."
There was reportedly no sign of Selena's on/off boyfriend Justin Bieber when the girls touched down in Mexico.
After they rekindled their romance over a month ago - just weeks after she split from her boyfriend The Weeknd - they were rumoured to be ringing in the New Year together, however, that looks unlikely now.
The past 12 months has been a tough year for Selena and her family after she went into hospital to have a kidney transplant.
The singer-and-actress underwent the life-saving operation after her battle with autoimmune disease Lupus - in which the body attacks healthy cells - which had caused the health of her organs to deteriorate.
The 'What Do You Mean?' singer reached out to Selena after he heard about her her serious illness, which made him realise how much he loved her.
However, Selena welcoming Justin back into her life hasn't been easy.
Although it was initially thought her mum Mandy Teefey was fuming with the reconciliation because she could never forgive the 23-year-old singer for the way he treated her daughter, it's believed their bond has been fraught since before then anyway.
A source said previously: "Selena has always said that the one person that means the most to her is her mom, Mandy. But still, they've had a really complicated relationship and have gone through a lot of ups and downs."
Mandy was reported to have been admitted to hospital following an altercation with the 'Sorry' singer earlier this month.
Justin and Selena dated on and off for four years before calling time on their turbulent relationship for good in 2015.