According to a report from KBC Bank and the Economic and Social Research Institute, consumers' brightening mood reflects an easing in fears about economic prospects.
As well as sentiment being at its highest in two years, January also marked the strongest monthly increase since December 2004.
Also unusual was a rise in all of the measures that make up the index.
More consumers have taken the view that prospects for the economy over the next 12 months are improving.
This is accompanied by a less negative outlook for employment.
KBC and the ESRI say that while 2010 has begun on a much more positive note than last year, consumers are still cautious.
But they warn that sentiment may drop again when Christmas sales end and New Year bills start to arrive.
