And there was food for thought for the huge numbers of New Zealanders seeking a brighter future across the Tasman - the cost of living in all Australian cities surveyed jumped up.
Sydney was the world's 11th most expensive cities followed by Melbourne (15th), Perth (19th), Canberra (23rd), Brisbane (24th) and Adelaide (27th).
That was partly down to a significant increase in demand for rental properties, Ms Constantin-Metral said.
"Coupled with very limited availability, the result has been very tight markets and increased prices.
The survey had better news for Kiwis seeking new lives in Europe, with a decline in the cost of living as the eurozone crisis hits the continent.
London is the most expensive British city at 25 on the list, down seven places from last year.
The most expensive European city was Moscow, in fourth place, followed by Geneva and Zurich in Switzerland.
Paris dropped 10 spots to 37th, Rome eight to 42nd and Athens 24 to 77th.
More than 60 per cent of Asian cities moved up in rankings, with Tokyo taking top spot.
Angolan capital Luanda came second and Osaka in Japan third.
The cheapest city surveyed was Pakistani port Karachi.
Mercer compiles its data every March.