Mengiste has published fiction and nonfiction dealing with migration, the Ethiopian revolution, and the plight of sub-Saharan immigrants arriving in Europe.

Mengiste's 2010 debut novel Beneath the Lion's Gaze – the story of a family struggling to survive the tumultuous and bloody years of the Ethiopian Revolution – was named one of the 10 best contemporary African books by The Guardian and has been translated into French, Spanish,[4] Portuguese,[5] German, Italian, Dutch, and Swedish.

[9] Mengiste's second novel, The Shadow King (2019), is set during Mussolini's 1935 invasion of Ethiopia, and shines a light on the women soldiers not usually credited in African history.

[10][11][12] Alex Clark in The Guardian said of it: "It is both a reasonably conventional narrative – there is plenty of action, detailed description and a focus spread between the principal characters – and a subtly unpredictable one.

History and modernity are juxtaposed in the factual asymmetries of warfare (the Ethiopians must rely on outdated and often malfunctioning weapons and have no way of long-distance communication beyond running messengers).

She serves on the advisory board of Warscapes, an independent online magazine that highlights current conflicts across the world, and is affiliated with the Young Center for Immigrant Children's Rights.