Rossatz-Arnsdorf is a town in the district of Krems-Land in the Austrian state of Lower Austria.

It is located in the Wachau valley of the Danube, a popular destination for tourists, and has excellent views of the ruins of castle Dürnstein, where King Richard the Lion-Heart of England was held captive by Duke Leopold V. Evidence of 7th century Slavic settlement has been found on the steep slope of the Danube valley.

At the beginning of the 9th century, Emperor Charlemagne donated the territory of the Benedictine Abbey of St. Michael in Metten.

Almost 9 km up the Danube, the small villages of Bach-, Ober- und Mitter-Arnsdorf belonged to the Prince-Bishop of Salzburg from its foundation in 860.

It was mediatized to Austria by order of the Final Recess of the Extraordinary Imperial Delegation (Reichsdeputationshauptschluss) in 1803.