Harmannsdorf is a municipality in the district of Korneuburg in the Austrian state of Lower Austria. It lies in the Weinviertel region, north of the Danube and roughly northwest of Vienna, within the federal province of Lower Austria.
The municipality is administratively part of the Korneuburg district, one of the districts that make up Lower Austria. As a municipality, it is a local government unit that may comprise several settlements or cadastral communities, a common structure in rural Austria.
Harmannsdorf is situated in a part of Austria characterised by a mild, relatively dry climate and a landscape of low hills and farmland typical of the Weinviertel. Its position near Vienna places it within the broader metropolitan region of the capital.