Harlequin, which publishes the work of more than 1,300 authors and issues 110 new novels each month, was sold by Canadian press group Torstar.
It will be absorbed into News Corp's book publishing group HarperCollins, bringing a more international customer base since 99.0 per cent of HarperCollins books are published only in English.
Torstar, which publishes the Toronto Star newspaper, the biggest Canadian English-language newspaper, is to use some of the money to reduce debt.
The deal ends a 39-year marriage between Torstar and Harlequin.
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Harlequin, based in Toronto, was founded in 1949 and came under the control of Torstar in 1975. Six years later Tortstar took full control.
Harlequin publishes its Romantic novels in a total of 34 languages, and earns 95 per cent of its sales outside Canada.
Last year sales amounted to 398 million Canadian dollars (USD 360 million, or 260 million euros), and gross operating profit was 56 million Canadian dollars.
News Corp managing director Robert Thomson said that Harlequin was a perfect addition, bringing a massive increase in digital publishing and extending the reach across new frontiers and in new languages, giving an immediate boost to results.