The love child of former Belgian King Albert II has won a court battle to grant her the same rights and titles as her father's children by his marriage.
Under the ruling, artist Delphine Boël, 52, will be granted the title of Princess of Belgium.
King Albert admitted he was her father in January this year, having fought her paternity claim for more than a decade.
Her mother, Baroness Sybille de Selys Longchamps, claims she had an 18-year affair with Albert before he was king.
Rumours first emerged that he had fathered a child with another woman after it was disclosed in an unauthorised biography about Albert's wife, Queen Paola, published in 1999.
Ms Boël first alleged on the record that King Albert was her biological father during a 2005 interview, but it was not until he abdicated in 2013 - when he lost his immunity to prosecution - that she opened court proceedings.
Her lawyer told reporters that she was "delighted" with the court's decision.
"A judicial victory will never replace a father's love, but it does offer a sense of justice," said Marc Uyttendaele. "Many more children who have gone through similar ordeals may be able to find the strength to face them."
Ms Boël and her two children can now hold the surname of her father, Saxe-Cobourg.
As a result of the ruling, after King Albert's death she will be entitled to receive an inheritance, along with his three other children - Prince Laurent, Princess Astrid and Philippe, the current king.
Despite her new title, Ms Boël will not receive any royal endowment. But Albert must pay nearly €3.4m (£3.1m) to cover her legal fees, according to local outlet De Standaard.
Her mother Baroness Longchamps says the affair with Albert, who was then Prince of Liège, lasted from 1966 to 1984, and he was around during Ms Boël's childhood.
Following his older brother's death in 1993 at 62, Albert unexpectedly came to the throne. He held the position until July 2013, when he announced his abdication - citing ill health - and was replaced by his son, Philippe.
The 86-year-old had resisted court orders to undergo DNA testing until he was facing fines of €5,000 per day for refusing to do so. In January, he announced he accepted Ms Boël as his fourth child after he "learnt the results of the DNA tests".
Belgium has a constitutional monarchy in which the king plays a largely ceremonial role.
Who is King Albert II?
- Born in 1934 as second in line to the throne
- Married Italian Donna Paola Ruffo di Calabria in 1959
- The couple have two sons and a daughter
- Became king in August 1993 following the death of his older brother, King Baudouin
- With his constitutional role, stepped in during country's 2010-2011 political stalemate
- Served as monarch for two decades until his 2013 abdication