Atelopus longirostris is historically known from the western slopes of the northern Ecuadorian Andes in the provinces of Esmeraldas, Imbabura, Pichincha, and Cotopaxi, at elevations between 200–2,500 m (660–8,200 ft) above sea level.
Tapia and colleagues give a slightly different historic range that includes Imbabura, Cotopaxi, Pichincha, and Santo Domingo de los Tsáchilas Provinces and a narrower altitudinal range, 900–1,925 m (2,953–6,316 ft).

Atelopus longirostris inhabits lowland (but see above) and montane tropical rainforests.
Breeding takes place in streams.
Populations discovered in 2016 were in isolated, small patches of native forest within a heavily modified landscape.
They were all found at night, perched on leaves about half a metre above the ground, some distance away from the nearest rivers.
Atelopus longirostris is historically known from the western slopes of the northern Ecuadorian Andes in the provinces of Esmeraldas, Imbabura, Pichincha, and Cotopaxi, at elevations between 200–2,500 m (660–8,200 ft) above sea level. Tapia and colleagues give a slightly different historic range that includes Imbabura, Cotopaxi, Pichincha, and Santo Domingo de los Tsáchilas Provinces and a narrower altitudinal range, 900–1,925 m (2,953–6,316 ft).
Atelopus longirostris inhabits lowland (but see above) and montane tropical rainforests. Breeding takes place in streams. Populations discovered in 2016 were in isolated, small patches of native forest within a heavily modified landscape. They were all found at night, perched on leaves about half a metre above the ground, some distance away from the nearest rivers.
Atelopus longirostris