The abbey was founded in 1080-82 by Ottokar II of Styria as a community of secular canons and as a dynastic burial place for his family. Together with his fortress, the Styraburg (Schloss Lemberg), it served as a focal point of Ottokar as ruler of the Traungau, and was endowed with significant possessions in the Traisen and Gölsen valleys, in Lower Austria, probably from the dowry of Ottokar's wife Elisabeth, daughter of the Babenberger Leopold II of Austria.
In 1107-08 the monastery was given as a priory to the Benedictine Göttweig Abbey, and became an independent abbey in 1110-11. Its first and greatest abbot was Blessed Berthold of Garsten (d. 1142), a champion of the Hirsau Reforms, who is buried in the abbey church, and who built the abbey up to such a level that for centuries it was the religious, spiritual and cultural centre of the Eisenwurzen region.
From 1625 Garsten Abbey was a member of the Benedictine Austrian Congregation.
In 1787 it was dissolved by Emperor Joseph II.
Since 1851 the former monastery buildings have accommodated a prison, Justizanstalt Garsten. This is one of the few prisons in Austria where life sentences are carried out. Austrian incest-rapist Josef Fritzl is serving his sentence there.
The abbey church still survives as a parish church. It was built by the Carlone family of master builders and is considered one of the most beautiful examples of High Baroque architecture in Austria. Particularly notable are the stucco work and the Dutch tapestries. The Losenstein chapel, the sacristy and the summer choir are also of special interest.
- Heinz Dopsch: Die steirischen Otakare Zu ihrer Herkunft und ihren dynastischen Verbindungen in: Das Werden der Steiermark - Die Zeit der Traungauer; Festschrift zur 800. Wiederkehr der Erhebung zum Herzogtum, Hg Gerhard Pferschy, Verlag Styria, Graz 1980