Born Iris Patricia Steir in Newark, New Jersey, the artist studied at the Pratt Institute and Boston University. Her early career was associated with conceptual art and minimalism, movements that informed her transition toward the abstract, process-oriented painting for which she became internationally recognized.

Steir is most celebrated for her Waterfall paintings, a series initiated in the late 1980s that employed a rigorous, gravity-defying pouring technique. Her practice often bridged the gap between Eastern landscape traditions and Western abstraction, frequently incorporating site-specific wall drawings alongside her canvas work.

Over a career spanning five decades, Steir received significant institutional recognition, including the National Medal of Arts in 2017. Her work remains a staple of contemporary abstract painting, characterized by its meditative quality and the deliberate interplay between controlled technique and the unpredictable nature of fluid paint.