Beaufort Books went ahead and released The Jewel of Medina by Sherry Jones on Monday, nine days ahead of schedule.
The novel has been described by an American academic as an "anti-Islamic polemic".
It tells a fictionalised account of the experiences of Aisha, one of the Prophet's brides. The marketing material reads: "Married at nine to the much-older Mohammed, Aisha uses her wits, her courage, and her sword to defend her first-wife status even as Mohammed marries again and again, taking 12 wives and concubines in all."
Last month the London office of Gibson Square Books director Martin Rynja was firebombed. It was planning to publish the book in the UK later this month.
Now Beaufort Books, which has also published OJ Simpson's hypothetical confessional 'If I Did It' about the murder of his ex-wife Nicole Brown, has gone ahead with publication.
Eric Kampman, the publisher's president, said he felt it was "better for everybody ... to let the conversation switch from a conversation about terrorists and fearful publishers to a conversation about the merits of the book itself."
In August the publisher Random House US announced it was pulling publication because it had been advised that the book "might be offensive" to some Muslims and "could incite acts of violence by a small, radical segment".
It came after Professor Denise Spellberg, of the University of Texas, described the book as "soft core pornography".
In an article in the Wall Street Journal, she wrote: "There is a long history of anti-Islamic polemic that uses sex and violence to attack the Prophet and his faith. This novel follows in that oft-trodden path, one first pioneered in medieval Christian writings."
Mr Rynja took the novel on, saying there must be "open access to literary works, regardless of fear".
He was unavailable for comment on Tuesday about whether Gibson Square would be publishing the book.
Three men have been remanded in custody over the attack on Gibson Square's London office