His Royal Highness Prince Sébastien was born on 16 April 1992 at the Maternité Grande-Duchesse Charlotte in Luxembourg.

His Royal Highness Prince Sébastien Henri Marie Guillaume, Prince of Luxembourg, Prince of Nassau and Bourbon-Parma, is the youngest of five children of Their Royal Highnesses Grand Duke Henri and Grand Duchess Maria Teresa of Luxembourg.

In 2010, Prince Sébastien received the Order of the Gold Lion of the House of Nassau.

After attending the local nursery school in Angelsberg, Prince Sébastien entered primary school at St. George's International School in Luxembourg. He then moved to the United Kingdom to attend Sunningdale School and subsequently Ampleforth College, which his grandfather, Grand Duke Jean, also attended. He completed his secondary education with an International Baccalaureate at the International School of Luxembourg. He is fluent in Luxembourgish, French, English, German and has some knowledge of Spanish.

From September 2009 to March 2010, Prince Sébastien completed an internship at the Kräizbierg Foundation, which works for people with disabilities.

His university studies took him to the United States. In 2014, during the summer holidays, he interned at LVMH Watch & Jewellery in Hong Kong, where he assisted in the organisation of events. In December 2015, he gained a degree in Marketing and Communications from the Franciscan University of Steubenville.

In 2016, he put this knowledge to good use during an internship as Marketing and Sales Manager at the Château Les Crostes en Provence, the estate of Prince Félix and Princess Claire.

After having successfully completed online courses on solar energy, Prince Sébastien then worked in forest management in Germany, focusing on new sustainable methods for both forest management and animal welfare.

Like his father, Grand Duke Henri (in 1975) and his eldest brother, Grand DukeGuillaume (in 2002), Prince Sébastien successfully completed his officer training at the prestigious Royal Military Academy of Sandhurst (RMAS) in the United Kingdom from 2016 to 2017. The Prince was sworn in as an officer of the Luxembourgish Army in September 2017. Since then, Prince Sébastien has commanded a platoon of the Irish Guards, a regiment of the British Army in which his grandfather Grand Duke Jean had already served during World War II.

Prince Sébastien likes to discover new cultures, which led him to travel to New Zealand for three months in 2019.

Whenever his schedule allows, Prince Sébastien takes part in the activities of the Grand Ducal Family and attends certain ceremonies or official activities, such as the festivities for the National Day or the last day of the Octave, the traditional pilgrimage to honour Our Lady of Luxembourg, the patron saint.

Eager to support the values conveyed by sport, Prince Sébastien accepted the High Patronage of the Luxembourg Swimming and Lifesaving Federation (FLNS).

A sports enthusiast, Prince Sébastien enjoys climbing, skiing, swimming and especially rugby. After having played for a local club for several years, he was selected for the Luxembourg U18 national rugby team and later for his university team.