Wellington rents jumped 9.8 per cent annually while Auckland's rose only 3 per cent, falling slightly last month, according to the latest Trade Me Property Rental Price Index.
Nigel Jeffries, head of Trade Me Property, predicted Auckland rents would rise this year.
Christchurch rents fell in the year to December compared to the previous year, the data showed.
Wellington was one of the strongest rental markets, with median weekly rents up by 9.8 per cent in the last year to equal the national median of $450, he said.
"Wellington started the year very quietly but took off in the second half of 2016. In the last 12 months there has been a $2000 increase in the annual cost of renting a typical property in Wellington," he said.