The black-winged lovebird, with a length of about 16–16.5 cm (6.25–6.5 inches), is the largest of all the lovebirds. It is sexually dimorphic, as are the red-headed lovebird and grey-headed lovebird of the lovebird genus. The dimorphism becomes apparent in juvenile birds after their first molt at about eight or nine months of age. Both the male and female black-winged lovebird are mostly green, and only the adult male black-winged lovebird has a red forehead and a ring of red feathers around its eyes.
The tail is black tipped and feathers below the tail show a yellowish colour. The rump and feathers above the tail are light green. In the male feathers under the wing are typically black, and in the female the feathers under the wing are typically greenish or brownish black. Both sexes have a red beak and gray feet.
The black-winged lovebird nests in a tree cavity. The eggs are white and there are usually three or four eggs in a clutch. The female incubates the eggs for 23 days, and the chicks fledge from the nest about 45 days after hatching.