Kapelln is a market municipality in the Sankt Pölten-Land district of Lower Austria, Austria. It lies in the eastern part of the state, within the federal district centred on the city of Sankt Pölten.
The municipality is subdivided into the Katastralgemeinden Etzersdorf, Kapelln, Katzenberg, Mitterau, Mitterkilling, Oberkilling, Obermiesting, Pönning, Panzing, Rapoltendorf, Rassing, Thalheim, Unterau, Unterkilling and Untermiesting. Roughly 10.29% of the municipal area is forested.
Economically, Kapelln has 102 agricultural companies and 586 jobs. As a market municipality, it holds that status within the Austrian administrative system.