Saturday is McEwan's ninth novel, published between Atonement and On Chesil Beach, two novels of historical fiction. McEwan has discussed that he prefers to alternate between writing about the past and the present.
While researching the book, McEwan spent two years work-shadowing Neil Kitchen, a neurosurgeon at The National Hospital for Neurology and Neurosurgery in Queen Square, London. Kitchen testified that McEwan did not flinch in the theatre, a common first reaction to surgery; "He sat in the corner, with his notebook and pencil". He also had several medical doctors and surgeons review the book for accuracy, though few corrections were required to the surgical description. Saturday was also proof-read by McEwan's longstanding circle of friends who review his manuscripts, Timothy Garton Ash, Craig Raine, and Galen Strawson.
There are elements of autobiography in Saturday: the protagonist lives in Fitzroy Square, the same square in London that McEwan does and is physically active in middle age. Christopher Hitchens, a friend of McEwan's, noted how Perowne's wife, parents and children are the same as the writer's. McEwan's son, Greg, who like Theo played the guitar reasonably well in his youth, emphasized one difference between them, "I definitely don't wear tight black jeans".
Excerpts were published in five different literary magazines, including the whole of chapter one in the New York Times Book Review, in late 2004 and early 2005. The complete novel was published by the Jonathan Cape Imprint of Random House Books in February 2005 in London, New York, and Toronto; Dutch, Hebrew, German, French, Spanish, Polish, Russian, and Japanese translations followed.