Male. The Goliath Birdwing's forewings are black. The costal edge is green and beyond the medium black bar is a large green triangle which reaches the dorsum but not the black ternum].
The underside is greenish yellow and greenish. The veins are black and there is a black border.The outer cells have small black spots. The hind wings are golden with a black edge bordered basally by a thin green line. There are some green spots in the cells of the golden area. The underside is similar to the upper side, but there is no black border. The edge is green. The spots in the cells of the golden area are black. The abdomen is yellow with black-edged tergites. The head and thorax are black and the underside of the thorax has tufts of red hair.
Female. Ornithoptera goliath is strongly sexually dimorphic. The female is larger than the male and the basic colour is dark-brown. At the outer edge there is a postdiscal chain of white spots. In the discal] cell there is a cluster of white spots, sometimes shaped like an E.
The hind wings have a broad yellow postdiscal band with a chain of dark-brown spots in the cells. The underside is very like the upper but the colours are stronger.