Hollenegg is a former municipality in the district of Deutschlandsberg, in the Austrian state of Styria. It lies in the western part of Styria, within the Deutschlandsberg district, an area of rolling hills and wooded terrain in southern Austria near the border with Slovenia.
Since the 2015 Styria municipal structural reform, Hollenegg is no longer an independent municipality and has been part of the municipality of Schwanberg. The reform merged a number of small Styrian municipalities into larger administrative units, and Hollenegg was among those absorbed.
The locality is best known for Hollenegg Castle, a historic estate that gives the area its name and remains its most prominent landmark. Otherwise, Hollenegg is a small rural settlement whose administrative identity is now tied to Schwanberg.