Mullen has taught at Cornell University and currently teaches courses in American poetry, African-American literature, and creative writing at the University of California, Los Angeles. While living in Ithaca and Rochester, New York, she was a faculty fellow of the Cornell University Society for the Humanities and a Rockefeller fellow at the Susan B. Anthony Institute at University of Rochester. She has received a Gertrude Stein Award for innovative poetry, a Katherine Newman Award for best essay on U.S. ethnic literature, a Foundation for Contemporary Arts Grants to Artists award (2004), and a fellowship from the John Simon Guggenheim Memorial Foundation. Her poetry collection, "Sleeping with the Dictionary" (2002), was a finalist for a National Book Award, National Book Critics Circle Award, and Los Angeles Times Book Prize. She received a PEN/Beyond Margins Award for her "Recyclopedia" (2006). She is also credited for rediscovering the novel "Oreo", published in 1974 by Fran Ross. Mullen won the fourth annual Jackson Poetry Prize from Poets & Writers in 2010.