Kalsdorf bei Graz is a municipality in the district of Graz-Umgebung in the Austrian state of Styria. It lies in the southern part of the Graz Basin, just south of the city of Graz, whose urban area it adjoins.
The municipality is a market town (Marktgemeinde) and is one of the larger communities in Graz-Umgebung, having grown considerably as a residential and commercial suburb within the Graz metropolitan region. It is served by the railway line between Graz and Leibnitz, with a station of its own.