Brunei Darussalam, Indonesia, Malaysia, Myanmar, Singapore, Thailand.
Extreme southern Myanmar (southern Tenasserim), south-western and southern Thailand, Peninsular Malaysia, Sumatra (including Nias I), northern Natuna Is and Borneo.
 
Rarity Status
Currently this species is not classified as a rarity in this country OR information has not been updated.
Population
Estimated population is unknown (2010).
Plain Sunbird (Anthreptes simplex) [XC151404]
by Ding Li Yong from Taman Negara, Sungai Relau, Merapoh, Pahang, Malaysia (call)
Plain Sunbird (Anthreptes simplex) [XC65389]
by Frank Lambert from Sungai Mahkam, Berau District, East Kalimantan, Indonesia (call)
Subspecies
No subspecies.
Birds from Borneo, having different colour gloss on forehead of male, described as subspecies simplicior, possibly worthy of recognition.
Proposed subspecies xanthochlora (from Tenasserim, in southern Myanmar) and euthapsinus (Bunguran, in Natuna Is) considered indistinguishable from those elsewhere in range.