Duchess Irene was born on 18 April 1952 in Freiburg-im-breisgau. She is the youngest daughter of Duke Georg Alexander and his wife Duchess Ilona.
Duchess Irene was christened into the Roman Catholic Church with the names Caroline Luise Irene Margarethe Helene Margareta Albertine Konrada. She grew up with her family in the West German state of Baden-Württemberg in the south of the country.
Duchess Irene was married to Constantin Harmsen in a civil wedding on 22 September 1979 in Mexico City. This was followed by a religious wedding on 26 July 1980 at the St. Leodegar Church in Biengen.
Duchess Irene and her husband have two sons together, Maximilian, born 1982 and Moritz, born 1985. Through their eldest son who married Countess Marianna von Westerholt and Gysenberg in 2008 they have one granddaughter and two grandsons. Duchess Irene and her husband live in Frankfurt am Main.
- Grand Cross of Order of Prince Danilo, Royal House of Montenegro (1 August 2018)