The number of visitors from the Republic to Northern Ireland increased 36 per cent in the first three months of the year compared to the same period in 2008.
Travellers from the State spent 217,000 nights in the region, with 109,000 trips made during the three-month period.
However, not all travellers were shoppers seeking out bargains, with the region reporting holiday trips were up 100 per cent to 52,000 visits.
Revenue from the State rose 51 per cent, with tourist revenue putting £14.3 million into the local economy.
Northern Ireland's tourism minister Arlene Foster welcomed the increase in figures, which significantly exceeded expectations.
"It is particularly encouraging to see the number of pure holiday visits form the Republic rise so significantly. This shows that more and more visitors from the Republic are coming to Northern Ireland, not just for shopping, but also for the huge range of things to see and do here," she said.
"The significant rise in revenue from this market is also a welcome boost to the Northern Ireland economy."
Chief executive of the Northern Ireland Tourist Board Alan Clarke said the rise in holiday visits from the Republic compared "very favourably" to figures for the Great Britain market.
The tourist board's most recent campaign is aimed at encouraging residents and visitors to the Republic to "head north", with the focus on encouraging shoppers to extend their stay.