Leslie Carter was born in Tampa, Florida, the third of five children of Jane Elizabeth Spaulding Carter and the late Robert Carter (1952-2017). She was born at the Garden Villa Retirement Home, where the Carter family were living and working at the time. She was the older sister of singer Aaron Carter and his twin sister model Angel and the younger sister of BJ Carter and Nick Carter. She was the younger half sister of Ginger Carter. Leslie was the stepsister of Taylen Dobson and the older half-sister of Kanden Carter.