Niederleis is a town in the district of Mistelbach, in the Austrian state of Lower Austria. It lies in the country's north-eastern quarter, within the Weinviertel region bordering the Czech Republic.
The municipality is one of several small communities in the Mistelbach district, an area characterised by rolling farmland, vineyards and scattered villages rather than large urban centres. Like much of Lower Austria, it sits in a landscape shaped by agriculture and by its position close to Vienna, Austria's capital, which lies to the south.
Niederleis is best known for Schloss Niederleis, a castle that stands in the town and gives it a modest place among the historic estates of the Weinviertel. Otherwise it remains a quiet rural settlement, typical of the district's smaller towns.