Discount grocer Lidl has reported sales growth of 17.4% over the last year - the strongest increase of the four main supermarkets here.
Across all categories, sales in the grocery sector were up 11.7% over the last 52 weeks, according to a grocery sector report by research company Kantar.
German giant Lidl recently opened its 40th store in Northern Ireland at Holywood Exchange retail park.
Kantar's report said Lidl's growth allowed it to increase market share by 0.3 percentage points to 6.4% of total grocery spend.
Lidl has also been celebrating its annual fundraising trolley dash, which this year raised money for NSPCC NI.
Kantar retail analyst Emer Healy said: "Lidl encouraged additional shoppers through its doors, something other retailers struggled to achieve, and these new customers contributed an additional £7.1m to Lidl's overall growth this period."
Tesco, which has around 50 stores here, increased sales by 11.3% over the year, and kept its place as NI's number one grocer with a market share of 35.3%.
Ms Healy said the second major lockdown in NI, which began on October 16 and ended last Friday, had prompted a change in grocery shopping habits. "Lockdown impacted shopping patterns at the grocer as customers visited less frequently and made bigger trips each time.
"Shoppers picked up 20 items per shop on average, an increase of 16.9% compared with last year that added an additional £186m to Tesco's takings."
And there was evidence that the novelty of cooking from scratch was wearing off, as sales of frozen food were up by nearly 23% over the last 12 weeks.
Sainsbury's, the second-biggest grocer here with 14 stores, had healthier sales growth than Tesco with an 11.6% surge, leaving it with a market share of 17%.
However, sales growth at Asda - which has 17 stores - was slimmer at 7%, leaving it with market share of 15.9%.
But the healthiest sales growth across the whole grocery sector was among symbol retailers - a category covering convenience stores like Spar and Centra - where sales were up 22.5%, leaving their market share at 8.7%. Ms Healy said growth in the grocery market in Northern Ireland had jumped to 20.3% after October 16.
Ms Healy said: "As was the case at Tesco, Sainsbury's and Asda shoppers visited the supermarkets less frequently and it was bigger trips that helped to drive growth.
"Shoppers adding more items to their baskets meant an extra £42.1m spent in Sainsbury's and £125.5m in Asda this period."
Shoppers had also spent an extra £18.5m on beer, wine and cider over the last few months, as they compensated for closures while also stocking up for Christmas.