Gibb gained recognition as a writer with the publication of her first novel Mouthing the Words in 1999. It may be called a bildungsroman, for it traces Thelma Ann Barley's growth to adulthood through sexual abuse, anorexia and multiple personality disorder. Reminiscent of Sylvia Plath's The Bell Jar (1963), Jeanette Winterson's Oranges Are Not the Only Fruit (1985) and Andrea Ashworth's Once in a House on Fire (1998), the novel has been described as a "heartwrenching rollercoaster ride" (The Guardian), and "a smashing combination of the heartbreaking and the hilarious" (Vogue).
In 1999, both The Globe and Mail and NOW selected Mouthing the Words as one of the "Best Books of the Year". In 2000, the novel won Gibb the prestigious City of Toronto Book Award. In 2001, she was added to the Orange Futures List, compiled by the jury of the Orange Prize, as one of the 21 promising young writers to watch in the new century.
Gibb's second novel, The Petty Details of So-and-So's Life was published in August 2002. A national bestseller in Canada, it was chosen by the Globe and Mail as one of the "Best Books of the Year".
Gibb's latest novel Sweetness in the Belly (2005) is set against the backdrop of the Ethiopian Revolution. The story moves between the walled Muslim city of Harar, in eastern Ethiopia, and London England during the Thatcher years. The book was shortlisted for the Giller Prize, won Ontario's Trillium Book Award, was chosen as a Best Book of the Year by the Globe and Mail and amazon.ca, and is on the longlist for the 2007 IMPAC Award.
To date, Gibb's novels have been published in 19 countries and translated into 15 languages. She has also written a number of short stories, articles and reviews. She was the 1999 winner of the Hart House Literary Contest and the 2001 winner of the CBC Literary Award for short story. She has been Writer-in-Residence at the University of Toronto and the University of Alberta and is the Vice President of PEN Canada.