Castanopsis acuminatissima ranges from southwestern China (Guizhou and Yunnan provinces) through Indochina (Laos, Myanmar, Thailand, Vietnam, and the Chittagong Hills of Bangladesh) and Malesia (Malaysia; the islands of Sulawesi, Java, Kalimantan, and Sumatra, in Indonesia; the islands of New Guinea (West Papua in Indonesia and Papua New Guinea) and New Britain (Papua New Guinea)).