Princess Delphine is the daughter of Baroness Sybille de Selys Longchamps, whose first husband was a Belgian nobleman and industrialist Jonkheer Jacques Boël.

[10] She is the founding patron of the Princess Delphine of Saxe-Coburg Fund based at Ghent University Hospital, promoting the use of art in health care.

[11] The Belgian brewery Struise produced a "Cuvée Delphine" beer for which she designed the artwork for the bottle label.

The press interpreted a short passage in the king's 1999 Christmas speech as acknowledgement of his 18-year-long relationship[21] with Baroness Sybille de Selys Longchamps.

[22][23] Boël gave an interview on 15 May 2005, to the France 3 presenter Marc-Olivier Fogiel in the broadcast "On ne peut pas plaire à tout le monde" (You Can't Please Everyone) in which she alleged for the first time that she was King Albert's daughter.

[25] In June 2013, when King Albert lost his immunity to prosecution, Boël summoned him and his children Prince Philippe and Princess Astrid to appear in court.

[28] On 5 November 2018, a court ruling was published which instructed Albert to submit to a DNA test to determine whether he was Boël's biological father.

[41] At the occasion of the Belgian National Day on 21 July 2021, she and her partner joined the royal family at the military parade for the first time.

[42] Delphine and her children have been granted the titles of prince and princess of Belgium with the style of Royal Highness following a court decision of 1 October 2020.