Keller’s first novel was highly praised by critics, including Michiko Kakutani in The New York Times, who said that in Comfort Woman, "Keller has written a powerful book about mothers and daughters and the passions that bind generations." Kakutani called it "a lyrical and haunting novel" and "an impressive debut." Comfort Woman won the American Book Award in 1998 and the 1999 Elliot Cades Award; previously, in 1995, Keller won the Pushcart Prize for a short story, "Mother-Tongue", which became the second chapter of Comfort Woman. In 2003, she won the Hawai'i Award for Literature.

Keller is a graduate of the Punahou School in Honolulu. She received her B.A. from the University of Hawaii with a double major in psychology and English and worked in Honolulu as a freelance writer, including at the Honolulu Star-Bulletin, a newspaper. She earned an M.A. and a Ph.D. in American Literature from the University of California at Santa Cruz.

Keller was raised primarily by her Korean mother, Tae Im Ku, in Hawaii and consequently identifies her ethnicity as Korean-American. Her father, Robert Cobb, however, was a German computer engineer. She has lived in Hawaii from the age of three. Married since 1990 to James Keller, she has two daughters.

Keller says she first heard of the term "Asian American" when she took a course in Asian American literature, the first course in this topic offered by the University of Hawaii. The syllabus included Maxine Hong Kingston, Jade Snow Wong, and Joy Kogawa. The genesis of Comfort Woman dated to a 1993 human rights symposium at the University of Hawaii where Keller heard a presentation by Keum Ja Hwang, who had been a comfort woman, the euphemism used by Japanese troops for sex slaves during World War II. "Her experience was so extraordinary," Keller has said, "I thought someone should write about it." Keller’s novels explore her own complex ethnic identity in the context of Hawaii’s multi-ethnic society and her relationship with her mother (upon whom "some details" of characters in her fiction are based).