Lili Mirojnick was born in New York City, to Ellen Mirojnick, a costume designer and actress, and Barry Carson. Her maternal grandparents were Abraham "Abe" Schneid and Sunny (née Schneider). Her parents divorced in 1987. She is of Eastern European and Mediterranean descent. Lili attended The Buckley School in Sherman Oaks, California, after attended the American Academy of Dramatic Arts (AADA) in New York, NY.