Brexit and the recent wet weather failed to dampen consumer confidence here over the last few weeks as grocery sales grew by 3.3% in the 12 weeks to October 6.
New figures from Kantar show that Dunnes has now been the country's biggest retailer for a full year as it increased its market share of the supermarket sector to 22.5%, up from 22.1% the same time last year.
Kantar said Dunnes' continued success, evidenced by 5.5% sales growth in the past 12 weeks, has largely been driven by its Shop & Save voucher campaign.
Meanwhile, SuperValu passed Tesco to take the number two spot for the first time since December 2018.
Kantar said that SuperValu has enjoyed larger basket sizes and growth in some of its core categories in the latest 12 week period.
Charlotte Scott, consumer insight director at Kantar, noted that both Dunnes and SuperValu have benefited from an out of season boom in sales of cleaning products.
"Shoppers have been indulging in a spot of seasonal autumn cleaning, perhaps thanks to the popularity of internet sensation Mrs Hinch and being kept indoors by the recent wet weather," Ms Scott said.
She said people have spent an additional €7.2m on household cleaning in the past 12 weeks, which is up 5.9% on last year and driven by Ireland's two largest retailers.
Meanwhile, despite falling behind SuperValu in the retailer rankings, Tesco enjoyed a return to growth this period, with shoppers making an extra trip compared to last year.
Kantar noted that confectionery has been a key category for Tesco, and is growing at an impressive 31.1% rate.
Charlotte Scott said that Tesco's promotion on tubs of sweets, pricing them at €3.99, has proved particularly popular and it has even had to put quotas in place to limit shoppers to a maximum of four per person.
And Aldi reached a new record market share at 12.6% in the latest 12 week period under review. It saw an additional 21,000 shoppers through its doors, with a particular push to target young families.
Meanwhile, Lidl's performance at a total level has also improved, with sales up 4.9% and its market share increasing to 11.9%.
Kantar noted that while Lidl's existing shoppers are visiting more often, and spending more when they do, penetration has dropped slightly by 0.4%.