T. helena is widely distributed and locally common in forest areas. Globally it is found in Nepal, India, Bangladesh, Myanmar, peninsular and eastern Malaysia, Singapore, Indonesia, Laos, Cambodia, Thailand, Vietnam, southern China including Hainan, and Hong Kong. In the Indonesian archipelago, T. helena is found in Sumatra, Nias, Enggano, Java, Bawean, Kangean Islands, Bali, Lombok, Sumbawa, Great Natuna (Bunguran), Sulawesi, Butung, Tukangbesi, Kalimantan, and Brunei.
In Hong Kong, T. helena is at the northern limit of its range. It is not common in Hong Kong but it is observed that there are stable populations in three sites (the surrounding area of Po Lo Che (Sai Kung), Shan Liu Road (Tai Po) and Kadoorie Farm & Botanic Garden in the New Territories). It is also found on Lantau Island and Hong Kong Island.
In India the T. helena is found in the north-east of the country including Sikkim, West Bengal, and Orissa. It is also found in the Andaman and Nicobar Islands. The subspecies found in India are:
T. h. cerberus (C. & R. Felder, 1865) – Arunachal Pradesh, Assam, Meghalaya, Nagaland, Manipur, Orissa, Mizoram, Sikkim, Tripura, W. Bengal. T. h. heliconoides (Moore, 1877) – Andaman Is. T. h. ferrari Tytler, 1926 – South Nicobar Is. The common birdwing, though widespread and common in many of the localities in which it occurs, was classified as vulnerable in 1985.