Sales at Asda increased in the three months to the end of September as more than 100,000 new customers shopped at the supermarket.
Comparable sales were up 2% in the period, marking a sixth consecutive quarter of growth.
Net sales were 3.7% higher, as online grocery shopping grew by 13.8%.
Asda president and CEO Roger Burnley said: "In a challenging third quarter for the market we continued to focus on the areas that we know are important to our customers and deliver on our strategic priorities.
"As a result, we were pleased to welcome an additional 115,000 customers through our doors and outperform the market for the second quarter running."
The retailer has expanded its own brand range amid a groceries price war which has seen the likes of Aldi and Lidl put pressure on the biggest players.
Mr Burnley added: "As we enter what will undoubtedly be an incredibly competitive festive trading period, our stores are fully prepared to bring Christmas home for our customers."
The latest figures come as Asda awaits provisional findings in the current stage of the Competition and Markets Authority (CMA) investigation into its proposed merger with Sainsbury's.
Retail experts say the watchdog could force the enlarged company to offload some stores.
A final decision must be made by March 5 2019.
Doug McMillon, chief executive and president of Asda's current owner Walmart, said the latest developments in the retailer's proposed merger with Sainsbury's were "in-line with our expectations".
Asda is also preparing to consult staff over changes to hours and roles in the new year.
The Press Association revealed last month that up to 2,500 jobs could be cut as part of the changes, according to sources.
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