Shoppers spent a massive $5.3 billion last month, the latest Paymark figures show.
Spending last month - fuelled in part by Christmas shopping, Boxing Day sales, and New Year's Eve holidaymakers - was up $300 million, or 5.4 per cent, on December 2013.
Last year also saw the highest growth in spending since 2007, with Paymark processing $52.3 billion of transactions for the year - up 6.6 per cent on 2013.
Paymark customer relations head Mark Spicer said the high growth rate was due to stronger consumer confidence. "I think what we are seeing now is consumer confidence is stronger along with a building of a stronger economy. Consumers feel more confident about getting out there and spending and that's reflected in the figures."
Mr Spicer said spending throughout 2014 had been very consistent. However, spending had got off to a slow start in December - Paymark's busiest month of the year.