February saw an "encouraging" increase of 2.6% compared to the same month last year, the NI Retail Consortium said.
It was higher than the UK average rise of 0.8% and second only to the Greater London region.
The success was put down in part to the Backin' Belfast campaign, which was aimed at restoring confidence in city centre after the Union flag protests last year.
Aodhán Connolly of the NIRC said: "There are signs here that after a very disappointing December and January, shoppers are now starting to gain a renewed confidence.
"This is partly due to the Back In Belfast campaign which the NIRC is supportive of and which has been a huge success, as well as the weeks of peace that we have had.
"These figures are encouraging for retailers large and small across Northern Ireland."
The loyalist protests started in December after Belfast City Council changed its flag-flying policy at City Hall to designated days. Shops were left empty over the typically busy Christmas period and businesses claimed upwards of £15m was lost to the city.
Mr Connelly welcomed the turnaround which has taken place in the past few weeks but said there can be no room for complacency.
He continued: "Northern Ireland has a great retail mix with something different to offer in each of our towns and cities.
"However we must not be complacent with what is happening in the high street. We look forward to working with government at all levels in the coming months to look at issues as diverse as car parking, rates, regeneration and planning."