Agnès was the daughter of unknown parents. The date and place of her birth have not been found.
Her husband was Amaury I de Meulan. They were married, but the date and place have not been found. Their eight known children were Hélissende (1196-?), Guillaume I (?-?), Henri (?-?), Guy (?-?), Amauri (?-?), Anne (?-?), Pierre (?-?) and Isabeau (c1245-?).