Flattach is a municipality in the district of Spittal an der Drau, in the Austrian state of Carinthia. It lies in the southern part of the country, within a district that stretches across the mountainous terrain of western Carinthia.
As a municipality, Flattach is one of the local administrative units of the Spittal an der Drau District, a district that includes a number of small towns and villages in this alpine region. The surrounding area is characterised by the high mountains and valleys typical of Carinthia, Austria's southernmost state.