Her mother was serving time in a federal prison for her involvement in a drug ring that smuggled marijuana from Jamaica to the United States. She was able to give birth to Leighton in a hospital and nurse her for three months in a halfway house, before returning to prison to complete her sentence,[after which Leighton's grandmother cared for her.
Meester has maintained that her parents gave her a normal upbringing and, despite their criminal past, are good people with experience that has only made Meester more open-minded and non-judgmental, "It made me realize that you can't judge anyone — especially your parents — for what they've done in their past, because people change." Meester has joked, "Look, I could've turned out a lot worse." She has cited her mother as her style icon.
Meester grew up in Marco Island, Florida, where she participated in productions at a local playhouse. When she was 11 years old, Meester and her mother moved to New York City. Meester attended the Professional Children's School and also began working as a model with Wilhelmina, booking a Ralph Lauren campaign shot by Bruce Weber and working with then photographer (now film maker) Sofia Coppola as well as many commercials including Tamagotchi toys and Clearasil. Meester made her television acting debut as a murder victim's friend on an episode of Law & Order. At 14, Meester moved to Los Angeles, California, wanting more stable work, and attended Hollywood High School and Beverly Hills High School.She then transferred to a small private school and graduated a year early.
In July 2011, she and her mother filed lawsuits against each other regarding Meester's financial support of her younger brother, who has multiple health problems. Meester's suit claims the money she sent was misused by her mother; her mother's suit makes a cross-claim alleging breach of contract and physical abuse.