Infanta Adelgundes was born on 10 November 1858 to Miguel of Portugal and Adelaide of Löwenstein-Wertheim-Rosenberg. She was their fifth child. She was only six years old when her father died.
Adelgundes married Prince Henry of Bourbon-Parma, Count of Bardi on 15 October 1876 in Salzburg. She was his second wife. Henry had been wounded in the Carlist War, which had rendered him an invalid. The couple had a tragic married life. All nine of Adelgundes pregnancies ended in miscarriages.
The couple lived in Austria and Venice, and Adelgundes spent a lot of time looking after her invalid husband. He eventually died in 1905. Adelgundes was very close to her nieces and nephews. Her sister Infanta Marie Anne had married William IV, Grand Duke of Luxembourg and Adelgundes was very close to their eldest daughter Marie-Adelaide, the eventual first Grand Duchess Regnant of Luxembourg.
Later in life, she gained the title Duchess of Guimarães, which was quite unusual since this title was usually reserved for the head of the house. Between 1920 and 1928 she acted as regent-in-absentia for her nephew Duarte Nuno, Duke of Braganza, who was the Miguelist claimant to the Portuguese throne. At the beginning of this regency, she was created 7th Duchess of Guimarães. She was a great supporter of the restoration of the Portuguese monarchy, and she even wrote a manifesto for this purpose. An accord was made with former King Manuel II of Portugal in which her nephew Duarte was recognised as his heir.
She died at the age of 87 in Gunten, Switzerland after the German occupation of Austria forced the move from Austria.