De Graaff's Praomys is a high-elevation mouse of the Albertine Rift in Burundi, Rwanda, and Uganda. Its coat is dark gray to sooty black, and records include moist montane forest and bamboo forest.
The overall pelage is dark, typically dark gray or sooty black. One field note by the authors described an almost black back and grayish belly.
It was captured in moist montane forest. In high-elevation Echuya Forest, which was mostly bamboo, it was the only Praomys captured; records also include secondary growth and fast-flowing stream edges.
An extinction-risk assessment has not been added yet.