Retail Ireland says online sales are continuing to rapidly increase.
The group reported a 20% in sales in the sector in the third quarter of this year.
In the lead up to Christmas, the organisation said in-store sales in fashion and footwear were negatively affected by unseasonably mild weather.
Earlier, thousands of shoppers were out in towns and cities around the country to make the most of the post-Christmas sales.
Head of Retail Ireland Thomas Burke, says online shopping is an area that represents a challenge for high-street retailers.
"It is a challenge for Irish retailers - the online space, and we've seen it emerge in terms of its importance over recent weeks."