Belize, Costa Rica, Guatemala, Honduras, Mexico, Nicaragua.
Southern Mexico (Veracruz, Tabasco, Chiapas), Guatemala, Belize, Honduras, Nicaragua and Pacific slope of Costa Rica and western Panama (western Chiriquí).
 
Population
Estimated population is 50,000 - 499,999 (2010).
Yellow-bellied Tyrannulet (Ornithion semiflavum) [XC612036]
by Peter Boesman from El Diamante, Tarrazu, Puntarenas, Costa Rica (call)
Yellow-bellied Tyrannulet (Ornithion semiflavum) [XC395547]
by Johan Chaves from San Ram\u00f3n, Provincia de Alajuela, Costa Rica (call, song, posible macho agresivo defendiendo territorio)
Subspecies
No subspecies.
Formerly placed in a separate genus, Microtriccus, together with Brown-capped Tyrannulet (Ornithion brunneicapillus). The two form a superspecies. Previously considered conspecific, but now split by most authors on basis of plumage, voice and habitat, also no apparent intergradation where ranges come together in Costa Rica.