"We see this transaction as highly compelling for Westfield's security holders and Unibail-Rodamco's shareholders alike," Sir Frank said.
"Unibail-Rodamco's track record makes it the natural home for the legacy of Westfield's brand and business. We look forward to seeing Westfield continue to grow as part of the world's premier owner of flagship shopping destinations."
Shares in Westfield Corporation, the owner of shopping centres in the US and UK, were placed in a trading halt today pending the announcement of a potentially "significant" corporate transaction.
The shopping centre giant requested its shares be placed in a halt with immediate effect until December 14 or when an announcement is released to the market.
Westfield shares last traded on Monday at AUD$8.55.
The move comes just a few days after Sir Frank received a knighthood from the Queen at Windsor Castle.
Sir Frank was recognised for his contribution to the British economy after Westfield built two enormous shopping centres, one in London's Shepherd's Bush and one in Stratford City.
Founded in Sydney in 1953 by Frank Lowy and John Saunders, Westfield currently has interests in 35 shopping centres in the US and the UK, while its Australian and New Zealand centres are managed by the separately listed Scentre Group.
Lowy will retire as chairman of Westfield, but will chair an advisory board for the new company, while his sons Peter and Steven will also retain leadership roles.