A senior Auckland industry executive said he understood a deal had been struck for an Australian business to buy the centre for about $160 million, making it one of the biggest transactions of its kind lately.
In September, the Herald reported how Scentre had put the property on the market via the Australian real estate agency.
Scentre said then it was seeking expressions of interest from potential buyers.
WestCity is the last New Zealand mall fully-owned by Scentre, with about A$31.8 billion ($32.8b) worth of assets here and in Australia.
Scentre still owns 51 per cent of some of New Zealand's biggest malls with a Singaporean government fund. Those are Westfields at Albany, Manukau, Newmarket, St Lukes in Sandringham and Riccarton in Christchurch.
Scentre said at the time that the sale had been prompted by the business not seeing the property as having significant development potential when viewed alongside its other NZ holdings.
Westfield plans to expand St Lukes, Albany and its Two Double Seven mall in Newmarket.
The Australian Financial Review has reported that WestCity could fetch up to A$175m and that the property had a carrying value of A$161m in December 2015, down from the previous year's A$171m.