Taking their name from Bad Waldsee in Upper Swabia, they were originally ministerials (unfree knights) in the service of the abbey of Weissenburg and the Staufers. They grew wealthy in the space between the Danube and the Iller. Under the patronage of a Habsburg king, either Rudolf I or Albert I, they came to the Ennstal. In 1331, they sold Bad Waldsee to the Habsburgs.
By the acquisition of various lorships, they established several lines in Upper Austria. The lines of Linz and Drosendorf went extinct in 1400, that of Enns in 1483 and that of Graz in 1363. They frequently held the office of Hauptmann (governor) in Lower Austria and Styria. In 1395, they acquired Duino Castle after the extinction of the local lords. They also acquired Fiume and the coast in 1400. In 1465 and 1471, the Emperor Frederick III was confirmed as heir to Fiume.
- Wallsee, Walchsee, Walse, Walsse, Wallssee, Waldze, Waldsee; Italian Valsa.
- Gerhard Köbler, Historische Enzyklopädie der Länder der Deutschen (2014), p. 803.
- August Dimitz, History of Carniola from Ancient Times to the Year 1813 with Special Consideration of Cultural Development, Volume I: From Primeval Times to the Death of Emperor Frederick III (1493) (Slovenian Genealogy Society International, 2013 ), pp. 179, 226.
- Josip Banić, 'The Mystery of Merania: A New Solution to Old Problems (Holy Roman Empire and the Kingdom of Croatia-Dalmatia during the Investiture Controversy)", Historical Review, Ljubljana 75.162 (2020), pp. 296–327.
- Doblinger, Max (1906). Die Herren von Walsee. Ein Beitrag zur österreichischen Adelsgeschichte. Vienna.
- Köbler, Gerhard (2007). Historisches Lexikon der Deutschen Länder: die deutschen Territorien vom Mittelalter bis zur Gegenwart (7th rev. ed.). Munich: C. H. Beck.