Born in Port Harcourt, Nigeria, to a Nigerian mother and the Jamaican novelist and poet Lindsay Barrett, A. Igoni Barrett studied agriculture at the University of Ibadan. In 2007 he moved to Lagos, where he met his wife, the Dutch journalist and writer Femke van Zeijl.

His first book, a collection of short stories entitled From Caves of Rotten Teeth, was published in 2005 and reissued in 2008. A story from the collection, "The Phoenix", won the 2005 BBC World Service short story competition.

His second collection of stories, Love Is Power, or Something Like That, was published in 2013; according to the Boston Globe, the collection "pulses with an indomitable life force that is, by turns, tender and fierce". Time Out New York commented: "These rich pieces are also brilliantly sequenced.... Shifts in mood happen throughout the book.... Unlikely moments of empathy occur again and again amid wrenching drama and subtle comedy; the resulting collection satisfies on numerous levels." Love is Power, or Something Like That was chosen as a "best book of 2013" by NPR and Flavorwire.

His debut novel, entitled Blackass, was published in 2015. Reviewing it in The Financial Times, Jon Day wrote: "From the first sentence, Kafka’s The Metamorphosis confronts you with the inherent strangeness of the pact you make when you read fiction. Gregor Samsa has become an insect, Kafka says. Suspend your disbelief. Take it or leave it. A Igoni Barrett’s first novel — his third book — demands a similar response....to read him only as a Nigerian writer would be to do him a disservice. For Blackass is a strange, compelling novel, and Barrett has something to tell us all." Writing in The Guardian, Helon Habila said: "Igoni Barrett’s greatest asset is his ability to satirise the ridiculous extents people, especially Lagosians, go to in order to appear important." Claire Fallon for the Huffington Post concluded: "Blackass is a blunt, transparently written novel — the kind that makes the reader feel as though they’re standing inside the skin of the character, going about his day with him — and though the topic could easily be that of a polemic, it’s also a subtle, circumspect novel about the intersecting, sometimes mutually exclusive needs humans have for family and connection, and for status and power." Aaron Bady of Okayafrica calls it "the most unapologetically Nigerian book that American publishers have published in a long time, and as the 'Afropolitan' has become an increasingly omnipresent strand of contemporary African literature, there has been a steady backlash, both against the Afropolitan as such, and against the entire category of African immigrant literature. The novel was longlisted for the inaugural FT/OppenheimerFunds Emerging Voices Awards