To honour the occasion, HELLO! Online has gathered a list of ten facts you may not have known about the Belgian King.
King Philippe turned 54 on Tuesday
1. Philippe was born on 15 April 1960 in Brussels, Belgium as the first child of King Albert II and Queen Paolo. Upon birth, he was styled as "His Royal Highness Prince Philippe of Belgium".
2. After attending secondary school, the young Prince continued his education at the Royal Military Academy from which he graduated aged 21 in 1981. He then continued his education at Trinity College, Oxford University and at Stanford University, California where he graduated with a degree in political science in 1985.
King Philippe on his third birthday, 1963
3. As part of his charity work, Philippe is extremely interested in the young people of Belgium and how they are creating a better tomorrow for the country. He often visits schools and universities, and works hard on social issues such as unemployment and poverty.
4. In 1992, due to his increasing royal role in Belgium, the then Prince Philippe created the "Household of Prince Philippe" to help run his affairs.
King Philippe and Queen Mathilde married in December 1999
5. In December 1999, thousands took to the streets as the future King married the Belgium born Miss Mathilde d’Udekem d’Acoz. The new royal couple married in a civil ceremony at Brussels Town Hall before a stunning religious ceremony at the Cathedral of Saint Michel and Saint Gudula.
6. Two years after their beautiful wedding in October 2001, Philippe became a father for the first time when the couple welcomed their first child, Princess Elisabeth. The royal couple then expanded their family with the arrival of Prince Gabriel in August 2003, Prince Emmanuel in October 2005 and their fourth child, Princess Eléonore in April 2008.
The couple are parents to Princess Elisabeth, 12, Prince Gabriel, ten, Prince Emmanuel, eight, and five-year-old Princess Eléonore
7. On 3 July 2013, Philippe's father King Albert II announced he would be abdicating in favour of his son. Two and half weeks later on 21 July, the country celebrated as King Philippe was sworn in as the new king.
8. At age 54, Philippe is Europe's second youngest reigning monarch, behind the Netherlands' King Willem-Alexander who is only 46.
King Philippe and Queen Mathilde were crowned reigning monarchs in July 2013
9. The European Royal shares his birthday with British actresses Emma Thompson and Emma Watson.
10. King Philippe, along with his wife Queen Mathilde, represents Belgium across the world. The couple travelled the London in April 2011 for the wedding of the Duke and Duchess of Cambridge at Westminster Abbey.