The initial firm of George Allen and Sons was established in 1871, becoming George Allen and Unwin in 1914 as a result of Sir Stanley Unwin's purchase of a controlling interest.
Best remembered for publishing the highly successful works of J. R. R. Tolkien, the firm prospered under Sir Stanley and his son Rayner S. Unwin (who as a child had reviewed The Hobbit). Its London offices were long at 40 Museum Street.
Rayner Unwin had just retired at the end of 1985, Merlin and Corydon Unwin having taken over, when the firm was amalgamated in 1986 with Bell & Hyman to form Unwin Hyman Limited. Robin Hyman, who had first bought the older firm of Arthur Bell, became chairman and chief executive of both Allen & Unwin and Bell & Hyman, and chief executive of the combined Unwin Hyman. From this time onwards Allen & Unwin was an Australia-based, child company of Unwin Hyman. Rayner Unwin returned for a while as part-time chairman of Unwin Hyman, retiring again at the end of 1988. It was over the objections of largest shareholder Unwin that Hyman sold the firm to HarperCollins, the book-publishing arm of Rupert Murdoch's media empire.
HarperCollins has since sold Unwin Hyman's academic book list to Routledge. Routledge, in turn, was bought by Taylor & Francis.
In addition to operating as a publisher, Allen and Unwin acts as the Australia and New Zealand distributor for numerous overseas publishers, including the Orion Group, and is also a co-sponsor and publisher of the annual Australian/Vogel Literary Award.