The Black-headed Brush Finch occurs in eastern Panama and the Colombian Andes. A comparative study found a mostly solid black head, a larger bill and higher, faster song than in the related A. assimilis. It is recorded in evergreen, secondary and elfin forest.
Compared with A. assimilis, A. atricapillus shows a mostly solid black head rather than broad gray markings, and the study found larger bill measurements.
The checklist supplement lists evergreen forest, secondary forest and elfin forest among its habitats, with records at 700–1,000 m.
An extinction-risk assessment has not been added yet.