Mallnitz is a municipality in the Spittal an der Drau District in Carinthia, Austria.

The municipal area consists of the cadastral communities of Mallnitz proper and Dösen.

A trade route across the mountain passes to the Gastein Valley in the north may already existed in the Bronze Age.

The surrounding estates around Falkenstein Castle then were held by the Imperial Counts of Görz residing at Lienz.

Throughout the Middle Ages, Mallnitz was a strategically-important outpost on the trade route to Salzburg, especially for the transport of salt and gold mined in the Hohe Tauern ranges.