The then-Hereditary Grand Duke completed internships at the Belgian Chemical Union in 2003, at the Deutsche Bank in London in 2004, and at the Spanish branch of ArcelorMittal in 2005.[3] Sworn in December 2002 as an officer in the Luxembourg Army, Guillaume held the rank of colonel until his accession to the throne, upon which he was promoted to General and Commander of the Army.[3]
Hereditary Grand Duke
Guillaume as Hereditary Grand Duke in 2013
Guillaume was heir apparent to the crown of Luxembourg from his father's accession in 2000 until 2025, when he became Grand Duke following Henri's abdication.
Guillaume became the honorary chairman of the Board of Economic Development of the Grand Duchy of Luxembourg, an agency for economic promotion and development, in March 2001.[7][3] He has also been a member of the Council of State since 24 June 2005.[7] He attended the Millennium Conference at the United Nations headquarters in New York City in 2005.[3] Guillaume also worked at the European Commission and the Permanent Representation of Luxembourg to the European Union in Brussels in 2012.[3]
Guillaume is patron of the Luxembourg Cycling Sport Federation, Youth Hostels Central, National Association of Road Victims, Chamber Orchestra of Luxembourg, Youth Harmony Orchestra of the European Union, as well as to Young Entrepreneurs Luxembourg and Special Olympics Luxembourg Associations.[7]
During the summer of 1997, Guillaume participated as a member of Luxembourg Scout Movement in a humanitarian camp in Nepal. He was involved in a reforestation project and other actions for the benefit of less fortunate communities. In 2017, he joined the board of directors of the World Scout Foundation to support the development of scouting around the world.[7]
In 1999, he participated in a charitable mission in Aguascalientes to provide the educational and social assistance to young people in one of the most deprived areas in Mexico. After having chaired the Kräizbierg Foundation, which works for people with disabilities, for more than 10 years (2000–2011), he accepted the title of honorary president in March 2011.[7]
During the 2001–2002 academic year, the Hereditary Grand Duke completed officer training at the Royal Military Academy Sandhurst in the United Kingdom. Following the completion of his training, he was commissioned as a lieutenant in the Luxembourg Army by grand-ducal decree of 25 July 2002. In December of that year, he took the officer's oath of the Luxembourg Army at the Military Centre in Diekirch, in the presence of his family and national authorities. He is also a Knight of the Order of the Golden Lion of Nassau.
After his military training, he pursued university studies in international politics in both the United Kingdom and Switzerland. He subsequently attended the Institut Albert-le-Grand in Angers, France, completing a bachelor's degree in Humanities and Political Science at IRCOM. He also undertook internships in 2003 at Union Chimique Belge and in 2004 at Deutsche Bank in London.
From 10 June 2005 until his appointment as lieutenant-representative in 2024, Prince Guillaume served as a member of Luxembourg's Council of State, thereby gaining direct exposure to the country's political life. In the sporting domain, he granted his high patronage to the Luxembourg Cycling Sports Federation.
On the occasion of his 25th birthday in 2006, Luxembourg issued a commemorative €2 coin bearing his effigy alongside that of his father.
In September 2018, the Hereditary Grand Duke and his wife took up residence in London. There, Guillaume pursued postgraduate studies at the Royal College of Defence Studies. Founded in 1927, the institution welcomes around one hundred participants annually from more than 50 countries, offering courses in international relations, geopolitics, and strategic management for future high-level leaders. During this period, Princess Stéphanie enrolled in an art history program at the Sotheby's Institute of Art.
He is furthermore regarded by French legitimists as thirty-fourth in the line of succession to the throne of France.
Since 18 January 2016, Guillaume has been a member of the board of directors of Europäische Stiftung Kaiserdom zu Speyer Foundation.[7] He is also a member of the board of directors of the Fondation du Grand-Duc et de la Grande-Duchesse.[7]
On 23 June 2024, during the celebrations of Luxembourg's National Day, Grand Duke Henri announced that he would appoint Prince Guillaume as lieutenant-representative in October, marking the first stage in the transfer of grand-ducal powers and preparing the way for the monarch's abdication. The investiture ceremony took place on 8 October at the Grand Ducal Palace, followed by proceedings at the Chamber of Deputies. On 24 December, in his annual Christmas address, the Grand Duke announced that his abdication and the transfer of power to Guillaume would take place on 3 October 2025.[8]
He previously served as the Lieutenant Representative (Regent) for his father, Grand Duke Henri, from 8 October 2024, until his accession to the throne[9].
On interviews for his 30th birthday, he stated that he was in a relationship with a "dear miss" that had been going strong for more than a year but needed more time to evaluate their possible future. On 26 April 2012, the court announced the engagement of the Hereditary Grand Duke to the Belgian Countess Stéphanie de Lannoy.[10] The civil wedding took place on 19 October 2012; the religious wedding took place on 20 October 2012, at the Notre-Dame Cathedral.[11]
François Henri Louis Marie Guillaume (born 27 March 2023)
Reign
Guillaume V with Stéphanie on the day of his accession to the throne
On 8 October 2024, as had been announced by Grand Duke Henri on his Official Birthday that year, Guillaume was appointed as lieutenant representative (regent).[14] Under this capacity, he assumed a number of his father's constitutional powers,[15] such as the swearing in of ambassadors and the signing of Grand Ducal Decrees. This is traditionally the first step in the abdication process in Luxembourg, as both Jean (1961–1964) and Henri (1998–2000) have previously served in the position.[16] On 24 December 2024, during his Christmas message, Henri announced that the abdication would take place on 3 October 2025.[17]
Guillaume V taking the oath
Guillaume acceded to the throne on that date, becoming Grand Duke of Luxembourg.[18]
↑ "The history of the Nassau dynasty". Grand Ducal Court of Luxembourg. Retrieved 4 October 2025. He thus assumed the title Guillaume V, Grand Duke of Luxembourg
1 2 3 4 "CURRICULUM VITAE OF HIS ROYAL HIGHNESS THE HEREDITARY GRAND DUKE OF LUXEMBOURG"(PDF). Grand Ducal Court of Luxembourg (official). Luxembourg: Cour Grand Ducale. 9 November 2020. Archived from the original(PDF) on 20 June 2020. Retrieved 9 December 2020. Prince Guillaume attended primary school in Lorentzweiler and continued his education in the Lycée Robert Schuman until the fourth year of Luxembourgish secondary education. Then he pursued his studies at the Le Rosey Institute and at the Collège Beausoleil in the Swiss Alps, where he passed his French Baccalaureate in 2001. From September 2001 until August 2002, the Hereditary Grand Duke accomplished his Officer training at the Sandhurst Royal Military Academy in the United Kingdom....In 2009, the Hereditary Grand Duke graduated with honours with a Bachelor's degree in Humanities and Languages, specialising in Political Science, at the University of Angers (France).
↑ "H.R.H. Guillaume the hereditary Grand Duke of Luxembourg". University of Luxembourg. Luxembourg: Université du Luxembourg. Archived from the original on 9 December 2020. Retrieved 9 December 2020. After his military training at the Royal Military Academy Sandhurst, Guillaume studied history and politics at the University of Durham, at Brunel University in London and at the University of Angers in France.
↑ Princes and Princesses of the Grand-Ducal House of Luxembourg are Grand Crosses of the Order by birth but the decoration is worn only after they reach their majority (18 years old)[19]
↑ Slovak republic website, State honoursArchived 13 April 2016 at the Wayback Machine (click on "Holders of the Order of the 2nd Class White Double Cross" to see the holders' table): 2nd Class received by Hereditary Grand-Duke in 2005, i.e. during the state visitArchived 24 May 2011 at the Wayback Machine (French) of Grand-Duke, Grand-Duchess & Hereditary Grand-Duke in Slovakia (7 September 2005).
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