Former Princess Tessy de Nassau received the Grand Cross of the Royal Order of the Drum for her humanitarian work with Professors without Borders.
Tessy, who was awarded a knighthood by the Ordre Lafayette in Geneva last month, posted the news on her Twitter account.
The award was presented by Emmanuel Bushayija, also known as King Yuhi VI of Rwanda. Rwanda's monarchy was abolished by referendum in 1961, the year before its independence from Belgium. King Yuhi VI succeeded his uncle Kigeli V as claimant to the Rwandan throne in 2017.