Hagedorn was born in Manila to a Scots-Irish-French-Filipino mother and a Filipino-Spanish father with one Chinese ancestor. Moving to San Francisco in 1963, Hagedorn received her education at the American Conservatory Theater training program. To further pursue playwriting and music, she moved to New York in 1978.

Joseph Papp produced her first play Mango Tango in 1978. Hagedorn's other productions include Tenement Lover, Holy Food, and Teenytown. Her mixed media style often incorporates song, poetry, images, and spoken dialogue.

In 1985, 1986, and 1988, she received Macdowell Colony Fellowships, which helped enable her to write the novel Dogeaters, which illuminates many different aspects of Filipino experience, focusing on the influence of America through radio, television, and movie theaters. She shows the complexities of the love-hate relationship many Filipinos in diaspora feel toward their past. After its publication in 1990, her novel earned a 1990 National Book Award nomination and an American Book Award. In 1998, La Jolla Playhouse produced a stage adaptation.

She lives in New York City with her younger daughter.

• Chiquita Banana. Third World Women (3rd World Communications, 1972)
• Pet Food & Tropical Apparitions (Momo's Press, 1975)
• Dangerous Music (Momo's Press, 1975)
• Mango Tango (Y'Bird Magazine January 1, 1977)
• Dogeaters (Penguin Books, 1990)
• Danger and Beauty (City Lights, 2002)
• Charlie Chan is Dead: An Anthology of Contemporary Asian American Fiction (editor) (Penguin Books, 1993)
• The Gangster of Love (Houghton Mifflin, 1996)
• Burning Heart: A Portrait of the Philippines (with Marissa Roth) (Rizzoli, 1999)
• Dream Jungle (Viking Press, 2003)

Anthologies that include Hagedorn's work

• Four Young Women, ed. Kenneth Rexroth (New York: McGraw-Hill, 1973).
• Time To Greez! Incantations From the Third World Time To Greez! Incantations From the Third World, eds. Janice Mirikitani, et al. (San Francisco: Glide Pubs., 1975).
• American Born and Foreign: An Anthology of Asian American Poetry," eds. Fay Chiang, et al. (New York: Sunbury Press Books, 1979).
• Breaking Silence: An Anthology of Contemporary Asian American Poets, ed. Joseph Bruchac (New York: Greenfield Review Press, 1983).
• The Open Boat: Poems From Asian America, ed. Garrett Hongo (New York: Doubleday, 1993).
• Stars Don't Stand Still in the Sky: Music and Myth, eds. Karen Kelly and Evelyn McDonnell (New York: New York University Press, 1999).
• Stage Presence: Conversations with Filipino American Performing Artists, ed. Theodore S. Gonzalves (San Francisco and St. Helena: Meritage Press, 2007).