The two companies have jointly acquired 95% of Asserta Holdings, which owns the UK's biggest property website including the 10-year-old Propertyfinder.com.
Jim Buckle, managing director of Propertyfinder.com, said: "Our member agents will benefit both from the expertise that realestate.com.au will bring and from the long media reach of News International, as well as significantly increased marketing expenditure.
"Landlords and vendors will benefit as the best property website gets wider use from both agents and consumers, and our staff will enjoy being part of a new exciting phase of growth for the company."
The acquisition follows Sir Martin Sorrell accusing the News Corp chairman Murdoch of intenet panic buying.
"Rupert Murdoch, who I admire more than any other media executive... has been willing to make [internet] acquisitions almost willy-nilly," Sorrell said.
News of the acquisition comes just a day after News Corporation's Australian arm News Limited lifted its stake in realestate.com.au to 51.5%, giving it a voting majority.
News Limited said that its offer for Realestate.com.au has been extended to November 11.
Last month, the group upped its bid for the online property firm from £52m to £64m. However, independent directors of the site had advised shareholders to reject the increased offer.
News International plans to build awareness of the Propertyfinder.com brand through its newspapers and websites.
A separate board has been put in place to oversee strategic operations. Realestate.com.au will have day-to-day management of the UK property site.
News Corp has bought a string of web firms in recent months including videogame and movie website company IGN Entertainment, which owns GameSpy and Rotten Tomatoes, for $650m (£365m) and MySpace.com for $580m.
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