San Martín Huamelulpam is a town and municipality located in the state of Oaxaca in southwestern Mexico. The municipality occupies an area of 29.34 km² (11.33 sq mi) and is situated within the Tlaxiaco District.
Geographically, the town is positioned in the southern portion of the Mixteca Region. It serves as a local administrative division within this distinct cultural and geographical area of Oaxaca.