The Hereditary Grand Duchess of Luxembourg was born on 18 February 1984 in Ronse. She is the youngest daughter of Count Philippe de Lannoy and Countesse Alix.

She married Hereditary Grand Duke Guillaume on 20 October 2012. Countess Stéphanie de Lannoy is the youngest of eight children.

Their first child, Prince Charles Jean Philippe Joseph Marie Guillaume, was born on 10 May 2020.