It is found on the eastern Andean slopes in Putumayo, Colombia, and in Sucumbíos, Napo, Orellana, and Pastaza Provinces, Ecuador.

[2][3][4] It is named after William Saul from the University of Kansas Natural History Museum.

[7] Males and females form pairs and defend territories that can be stable over several months.

[5] Hyloxalus sauli occurs in primary and secondary forests at elevations of 200–800 m (660–2,620 ft) above sea level.

The IUCN cites habitat loss in favor of agriculture, mining, livestock cultivation, and logging as threats.