John Pinnock and Deborah Thornhill are Leigh-Anne's parents. Her parents got divorced in 2009. She has two sisters, Sarah and Sian-Louise. Leigh-Anne and her sister Sarah attended stage school, and at the age of 11. Sarah, remembers Leigh-Anne "always used to sing in the bathroom as she got ready for school".
- She briefly had a romantic encounter with Jamar Harding, bassist for the band Cover Drive, during 2012.
- She previously dated Jordan Kiffin. He is a football player for the football club Ashford Town, Middlesex. They met each other at the celebration party for Wings during 2012. They broke up in July 2016.
Leigh-Anne has a total of two pets.
Leigh-Anne bought herself a pug dog named Harvey to celebrate the success of Little Mix's #1 single. Leigh-Anne is keen for her pet Harvey to move in with the girls while the other members of Little Mix are less than interested at the prospect.
She explained to New! magazine: "I want to bring my pug Harvey to move in with us, but Jade and Jesy don’t really like animals." Jade added: "I love a good dog but we’re going to be very busy and it’s going to be hard looking after a dog."
Leigh-Anne shared a picture on Twitter of the new present she received from her former boyfriend Jordan Kiffin which was a puppy named Maurice.