Grafenbach-Sankt Valentin is a town in the district of Neunkirchen in the Austrian state of Lower Austria.
Grafenbach_St. Valtentin lies southwest of Ternitz in the Schwarzatal. It has an area of 13.9 km<sup>2</sup>. 15.54% of its area is forested.
In ancient times, the municipality was part of the Roman province of Noricum. There is a 9th-century burial ground near Grafenbach.