Kylie made a guest appearance on Sasse's ABC show "Galavant," where the two met and hit it off.
The Australian pop star had been wearing a diamond ring since January, and Sasse referred to her as his fiancée this week at the NME Awards after-party. They made it official via an announcement in Saturday's Daily Telegraph, a newspaper to which Sasse's family has ties.
The advertisement reads:
"The engagement is announced between Joshua, son of the late Dominic Sasse and of Mary Heale (nee Macauley), of Herefordshire and Kylie, eldest daughter of Ronald and Carol Minogue, of Melborne, Australia."