Hillman is also involved in non-violent activism as a member of the Code Pink Working Group in the San Francisco Bay Area.

One of contemporary poetry's most eclectic and formally innovative writers, Brenda Hillman is known for poems that draw on elements of found texts and document, personal meditation, observation, and literary theory.

Often described as “sensuous” and “luminescent,” Hillman's poetry investigates and pushes at the possibilities of form and voice, while remaining grounded in topics such as geology, the environment, politics, family, and spirituality.

Hillman has been increasingly interested in the innovative and experimental lyric traditions, particularly in how the Romantic concepts of nature and spirit have manifested in contemporary poetry.

This happened in part because of a rediscovered interest in esoteric western tradition and in part because I came to a community of women who were writing in exploratory forms...A poetic method which had heretofore been based on waiting for insight suddenly had to accommodate process, and indeterminate physics, a philosophy of detached looking.” Hillman’s early poetry collections received critical praise for their transfiguration of experience.

I would arbitrarily choose words and make myself use them to anchor the rest of the writing to the page…in the long poem, ‘A Geology,’ the corner words ‘anchor’ the rest of the poem to the page so it wouldn't float.” Reviewing Practical Water for the Boston Review, Craig Morgan Teicher spoke to Hillman’s process: “Hillman has charted her own unusual course, borrowing things—a mixture of conversational and high-lyric diction, an emphasis on language’s materiality, an interest in metaphysics and occult knowledge, and a passionate environmental and political consciousness—from pretty much every major poetic movement of the last century.” Practical Water even includes transcripts from congressional hearings, in which Hillman tries to “seek out the humanity behind policy and policymakers.” The fourth volume in the series, Seasonal Works With Letters on Fire, was a long-list finalist for the National Book Award and won a California Book Award Gold Medal; the Northern California Book Award for Poetry; and the International Griffin Poetry Prize.

The Judges’ Citation for the Griffin hails Hillman's latest: “Seasonal Works appears to be one of the most inclusive books a hyper-active imagination could wring out of the actual.

The book performs an ‘anarchic music’ and stimulates a craving for undiluted love, and a rollicking fury for justice that only its widely variant forms can sustain.