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) [XC332750]
by Jorge Gabriel Campos from Luna Lodge, Costa Rica (call, song)
Yellow-bellied Tyrannulet (Ornithion semiflavum) [XC226963]
by Patrick ODonnell from Bonampak, Chiapas, Mexico (call, song)
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.