Gayenhofen Castle, Medieval château in Bludenz, Austria.

Gayenhofen Castle is a three-storey classicist building on a strictly rectangular plan, standing above Bludenz next to the Laurentiuskirche. Its main wings project like risalits beyond the narrow west and east fronts, and the city-facing show front looks down over the town. It is considered one of the few classicist castle buildings in Austria outside Vienna.

The Counts of Werdenberg built a castle here between 1222 and 1245 as the seat of their Bludenz lordship. Count Albrecht III of Werdenberg-Heiligenberg lived in it from 1377/78 to 1418; after the Werdenberg feud the town and castle passed to the Habsburgs, and in 1448 Duke Sigmund traded them to Ulrich von Schlandersberg. A fire destroyed the castle in 1491. In 1746/47 Franz Andreas von Sternbach had the present palace built on the site using rubble stone from the old castle.

The name Gayenhofen only appears in the 19th century; the historian Manfred Tschaikner calls it an invention of that period, since the building was long known as Burg Bludenz. Today the former Schloss serves as the seat of the Bezirkshauptmannschaft Bludenz, the district authority, and since June 2023 the hillside castle garden below the southeast foot is again open to the public after about twenty years of closure.

The castle garden on the southeastern slope below the building reopened in June 2023 after about 20 years of closure for safety reasons; its retaining walls were repaired. The garden belongs to the state of Vorarlberg and is maintained by the city of Bludenz, which lends it to the public free of charge. The building itself houses the district administration (Bezirkshauptmannschaft), so interior rooms are not open to visitors.

The claim that Johann Caspar Bagnato designed Gayenhofen appears in several sources but has no documentary support; the building is attributed instead to local figures, including mason Andreas Schmied, who had enlarged the nave of the neighbouring St. Laurentius church.