Oyeyemi wrote her first novel, The Icarus Girl, while still at school studying for her A levels[1] at Cardinal Vaughan Memorial School. Whilst studying Social and Political Sciences at Corpus Christi College, Cambridge, two of her plays, Juniper's Whitening and Victimese, were performed by fellow students to critical acclaim and subsequently published by Methuen.

In 2007 Bloomsbury published Oyeyemi's second novel, The Opposite House which is inspired by Cuban mythology.

In 2009 Oyeyemi was recognized as one of the women on Venus Zine’s “25 under 25” list. [2]

Her third novel, White is for Witching, described as having "roots in Henry James and Edgar Allan Poe" was published by Picador in May 2009. It was a 2009 Shirley Jackson Award finalist and won a 2010 Somerset Maugham Award. A fourth novel, Mr Fox, was published by Picador in June 2011.

Fairy-tale romances end with a wedding, and the fairy tales don't get complicated. In this book, the celebrated writer Mr. Fox can't stop himself from killing off the heroines of his novels, and neither can his wife, Daphne. It's not until Mary, his muse, comes to life and transforms him from author into subject that his story begins to unfold differently.

Mary challenges Mr. Fox to join her in stories of their own devising; and in different times and places, the two of them seek each other, find each other, thwart each other, and try to stay together, even when the roles they inhabit seem to forbid it. Their adventures twist the fairy tale into nine variations, exploding and teasing conventions of genre and romance, and each iteration explores the fears that come with accepting a lifelong bond. Meanwhile, Daphne becomes convinced that her husband is having an affair, and finds her way into Mary and Mr. Fox's game. And so Mr. Fox is offered a choice: Will it be a life with the girl of his dreams, or a life with an all-too-real woman who delights him more than he cares to admit?

The extraordinarily gifted Helen Oyeyemi has written a love story like no other. Mr. Fox is a magical book, endlessly inventive, as witty and charming as it is profound in its truths about how we learn to be with one another.