Zerlach is a former municipality in the district of Südoststeiermark, in the Austrian state of Styria. It lies in the southeast of Styria, the federal state that makes up much of southern and southeastern Austria.
Since the 2015 Styria municipal structural reform, Zerlach is no longer an independent municipality; it forms part of the municipality of Kirchbach-Zerlach. The reform merged a number of small Styrian communes into larger administrative units.