Republic of Ireland visitors splashed out more than £233m
Overnight trips from the Republic to Northern Ireland reached record levels in 2022.
The CSO says the numbers topped one million for the first time.
Figures also show an increase of peoples spending across the border.
Republic of Ireland visitors splashed out more than £233m, up 65% on the £142m spent three years earlier.
David Roberts, Tourism NI Interim CEO, said the excellent results surpassed even their most optimistic forecasts;
"At a time when international markets have still been recovering, the additional business from the Republic has been hugely important to the tourism and hospitality sector right across Northern Ireland.
"A notable feature was the visits by Republic of Ireland residents to Northern Ireland grew at a much faster rate than visits within the Republic itself."