Caribbean slope of Costa Rica south to western and northern Colombia, western Ecuador, and locally in western and northern Venezuela (east to southern Miranda).
 
Population
Estimated population is unknown (2010).
Brown-capped Tyrannulet (Ornithion brunneicapillus) [XC393242]
by Iv\u00e1n Lau from Old Gamboa Road, Panama Province, Panama (song)
Brown-capped Tyrannulet (Ornithion brunneicapillus) [XC454099]
by Jerome Fischer from Parque Metropolitano, Panama City, Panama (call)
Subspecies
No subspecies.
Formerly placed in a separate genus, Microtriccus, together with Yellow-bellied Tyrannulet (Ornithion semiflavum). 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. Birds from northern Colombia (Santa Marta region) and north-western Venezuela described as subspecies dilutum, supposedly slightly paler below on average, but not reliably distinguishable from other populations.