[1][2] Heydemann's father, a centralien and engineer, while her mother, a graduate of École normale supérieure, and a university professor in Mathematics, have both played significant roles in her life.

[2] After completing her higher school preparatory classes at Lycée d’Orsay (Essonne), she gained admission to École polytechnique in 1994.

[7] After a brief stint, she joined the French telecommunications equipment company Alcatel, which later became Alcatel-Lucent in November 2006 following the merger with New Jersey–based Lucent.

She held various executive positions, notably in the sales division, where she was in charge of SFR and Orange key accounts.

[4] During that time, Heydemann was only the second female at the helm of a Paris CAC 40 company, following Engie's Catherine MacGregor, later to be joined by Estelle Brachlianoff of Veolia in July 2022.