Ornithogalum viridiflorum is a perennial, summer-growing bulbous plant, that goes dormant from autumn through winter into spring. The bulb is tunicated, tapering into a thin neck and grows from 40 to 200 mm in diameter. The foliage is succulent and arranged in a rosette. There are about 7 leaves that are erect, pale yellowish-green with a greyish bloom, strap-shaped, with a broad base and a pointed tip (mucronate).

The pale green inflorescence appears in the middle of the leaves and grows up to 1 m tall. The inflorescence is a raceme made up of many bell-shaped, pendulous, yellowish-green flowers. The raceme ranges from 150 mm to 300 mm long. The bracts are greenish, becoming thin, up to 30 mm long and 5 mm broad at the base. Pale green pedicels differ in length, they can grow up to 25 mm long. The perianth is pale green, drooping, about 25 mm long, the floral tube is about 9 mm long, lobes are about 15 mm long and 6-7 mm broad on the outer part. The filament is white, up to 8 mm long, the anthers are dark green and up to 3 mm long when mature. The ovary is green, 6 mm long. The seeds are brown, rounded on the third face, the top and the bottom are flattened, 7 x 4.5 x 2 mm.