Bolivia, Brazil, Colombia, Ecuador, French Guiana, Peru.
French Guiana (R Oyapock), and eastern Ecuador (lower R Aguarico, R Napo, R Pastaza), north-eastern Peru (R Napo, R Amazon, R Ucayali), extreme south-eastern Colombia (islands in R Amazon), Brazil (locally along R Amazon east to R Tocantins, also on lower R Branco, middle R Juruá, upper R Madeira) and north-eastern Bolivia (lower R Beni).
 
Population
Estimated population is unknown (2010).
White-bellied Spinetail (Mazaria propinqua) [XC11942]
by Roger Ahlman from Padre Island, near Cumaceba Lodge, Peru (call, song)
White-bellied Spinetail (Mazaria propinqua) [XC138961]
by Dan Lane from Ilha do Palhal, Rio Branco, Parque Nacional do Viru\u00e1, Caracara\u00ed, Roraima, Brazil (call)