Prince of Liège was a substantive title awarded by King Albert I of the Belgians to his youngest grandson, Prince Albert (former King Albert II), while he was third in line to the throne of Belgium. The title was used from 7 June 1934 until his accession as King of the Belgians in 9 August 1993. His wife, the present Queen Paola, was known as the Princess of Liège from their marriage in 1959 until 1993.
Albert's elder brother Prince Baudouin (later King Baudouin) was known as the Count of Hainaut while his father, Prince Leopold (later King Leopold III), was the Duke of Brabant at the time of Albert's birth. Leopold's brother held the title of Count of Flanders. This meant that all the commonly used in the Belgian Royal Household had been given, so a new style had to be created.
The title is reminiscent of the Prince-Bishopric of Liège, a noble title of the Holy Roman Empire. That title ceased to exist in 1795.
King Albert II decided in 2001 to no longer award courtesy titles such as Count of Flanders, Count of Hainaut, and Prince of Liège. The heir to the throne is awarded the title Duke or Duchess of Brabant. It is currently held by Princess Elisabeth, Duchess of Brabant. It is therefore likely that Albert II will be the only Prince of Liège.