The owner of Westfield shopping centres is being bought for $24.7bn (£18.5bn) in a deal which will see the malls launched in new markets.
French property group Unibail-Rodamco is offering $7.55 a share for the Australian business.
Westfield Corporation has 35 shopping centres in the UK and the US while Unibail-Rodamco has 71 sites in Europe.
Unibail-Rodamco said the takeover would result in a "progressive roll-out of the world famous Westfield brand".
The takeover is the second major deal involving shopping centre owners to emerge in just over a week.
On 6 December, Hammerson, which owns the Bullring in Birmingham, announced a £3.4bn bid for Intu, whose properties include the Arndale shopping centre in Manchester.
In a joint statement, Unibail and Westfield said they would make €100m (£88.2m) in savings a year despite no overlap between where the companies' shopping centres are based.
Christophe Cuvillier, chief executive of Unibail-Rodamco, said the acquisition of Westfield "adds a number of new attractive retail markets in London and the wealthiest catchment areas in the United States".
Mr Cuvillier said it will cut the cost of advertising and marketing. At the moment, Unibail shopping centres advertise individually under different brands for big events, such Christmas.
He said that by using the recognisable Westfield brand, which it intends to roll-out across its flagship shopping centres in areas such as Paris, Barcelona, Vienna and Warsaw, it will reduce advertising spend.
It will also save costs at the corporate level because the board of Westfield is stepping down and leaving the combined group.
The group expected to sell €3bn (£2.65bn) worth of assets over the next few years, which will involving divesting of some smaller shopping centres.
Sir Frank Lowy, the billionaire property tycoon who co-founded Westfield in the 1950s, will retire as chairman of Westfield. His sons Peter and Steven will also step down as co-chief executives of the business.
However, following completion of the deal, Peter Lowy will be appointed to the combined group's supervisory board and Sir Frank will chair a newly created advisory board.
They also said: "The Lowy family is committed to the success of the Group and intends to maintain a substantial investment in the group."
Sir Frank is one of the richest people in Australia with a fortune of $5.9bn, according to Forbes magazine and was knighted by the Queen last week.
Sir Frank originates from Eastern Europe and survived the Holocaust in Hungary. He moved to Australia in 1952.