Born in Brest, Thilleman is a student of commerce and an avid sportswoman, practicing volleyball and surfing in her native Bretagne. Thilleman, who stands 1.79 m (5 ft 10 1⁄2 in) tall, competed as Miss Bretagne in her country's national beauty pageant, Miss France 2011, held in Caen, where she would become the eventual winner of the title, gaining the right to represent France in the 2011 Miss Universe pageant.