Exarchopoulos grew up in the 19th arrondissement of Paris close to Place des Fêtes. Her father Didier Exarchopoulos is a guitar teacher and her mother Marina Niquet a nurse. Her grandfather was Greek.
When she was nine, her parents sent her to acting classes to cure her of her shyness. She continued to take lessons until 2005 where she made her debut in the film Martha. In 2006 Exarchopoulos was spotted by an agent and made her first television appearance in an episode of French police series R.I.S, police scientifique. At thirteen she had a role in the 2007 film Boxes.