Coomans was born in Paris as the daughter of the painter Pierre Olivier Joseph Coomans (1816–1889) and Adelaide Lacroix (1838–1884). Her sister Diana Coomans was also a painter and her brother Oscar Coomans (1848–1884) was a poet. Like her father and sister, she painted romantic genre scenes and was noted for her portrayals of the original inhabitants of Pompei before the eruption of Vesuvius, but also is known for depicting young women in other mythological or heroic scenes.

Coomans died in New York City.