Gonystylus maingayi grows as a tree up to 40 metres (130 ft) tall, with a trunk diameter of up to 80 centimetres (31 in). Bark is grey to brown. The fruit is round, dark brown, up to 4 centimetres (1.6 in) in diameter. Its habitat is swamps from sea-level to 150 metres (500 ft) altitude. G. maingayi is found in Sumatra, Peninsular Malaysia, Singapore and Borneo.