Her early work was loosely associated with conceptual art and minimalism, however, she is best known for her abstract dripped, splashed and poured "Waterfall" paintings, which she started in the 1980s, and for her later site-specific wall drawings.

She is a founding board member of Printed Matter bookshop in New York City, and of the landmark feminist journal, Heresies, first published in 1977.

[3] She attended the Pratt Institute in New York (1956–1958), where she was influenced by her teachers Richard Lindner and Phillip Guston, and Boston University College of Fine Arts (1958–1960).

Around 1970 she became friends with Sol LeWitt, Lawrence Weiner, and other conceptual artists, and she made the first of many trips to New Mexico to visit Agnes Martin.

In the late 1980s, Steir became influenced by the artists John Cage and Agnes Martin and began producing dripped, splashed and poured works, embracing the element of chance.

The artist relates this work to the 8th and 9th century Chinese Yipin "ink-splashing" painters,[6] having studied ink splash in the harmony of nature and humanity, inspired by Tibetan philosophy.

In 1995, the monograph Pat Steir was published by the American art critic Thomas McEvilley, chronicling the artists' life work up to that point.

Describing Steir's 2010 installation at Sue Scott Gallery, The Nearly Endless Line, which consisted of a white line snaking around the gallery's blue-black walls, lit with blue light, Sharon Butler writes in The Brooklyn Rail, "Walking through the darkened space, observers find themselves inside Steir’s painting, where they become part of the illusion she has created with paint and light.

[11] In a career spanning over fifty years, Steir has exhibited at a large number of galleries and institutions, throughout the U.S. and internationally.