Extreme southern Bolivia (south-western Santa Cruz), western Paraguay, northern Argentina (south to eastern La Rioja, northern San Luis, central Córdoba and northern Buenos Aires) and south-western Uruguay.
 
Population
Estimated population is unknown (2010).
Little Thornbird (Phacellodomus sibilatrix) [XC732171]
by Franco Vushurovich from Machareti, Luis Calvo, Chuquisaca Department, Bolivia (duet, song)
Little Thornbird (Phacellodomus sibilatrix) [XC54097]
by Juan Pablo Culasso from Establecimiento Los Picasos, Tres Marias, Formosa, Argentina (song)
Subspecies
No subspecies.
Considered by some authors to form a superspecies with Rufous-fronted Thornbird (Phacellodomus rufifrons), but the two overlap considerably in distribution, and differ in body size and nest structure.