The latest monthly analysis by consumer watchdog Which? found that Aldi shoppers spent on average £75.61 for a basket of 52 essential grocery items.
The second cheapest supermarket was Lidl, which cost shoppers an additional £1.38 for the same basket.
It marks the first time this year that the German retailer has out-performed Lidl, which previously held the title for six consecutive months.
The prices are a stark contrast to the most expensive supermarket, Waitrose, where the same basket cost £101.14.
Which? also compared the prices for a larger trolley of 156 items and found that the cheapest supermarket for a high volume of groceries is Asda.
Asda continues its streak as the cheapest traditional supermarket that began in January 2020.
A trolley with 156 items at Asda cost £336.89, compared to the most expensive supermarket, Waitrose, which cost £385.27.
The cost of living crisis is continuing to hit Britons hard, with soaring food and fuel prices largely behind the huge inflation increase, according to the Office for National Statistics.
Consumers can expect to see their grocery bills rocket by £454 as the rate of inflation for groceries jumped to 9.9 per cent over the four weeks to 10 July, a sharp rise from 8.3 per cent the previous month.
According to retail data company Kantar, butter, milk and dog food were the items that have increased in price the fastest.
Fraser McKevitt, head of retail and consumer insight at the firm, expects the overall record for grocery inflation to be surpassed in August.
“All this means that people will be feeling the pinch during our first restriction-free summer since 2019,” he said.
“Taking a barbecue as an example, buying burgers, halloumi and coleslaw for some al fresco dining would cost you 13 per cent, 17 per cent and 14 per cent more than it would have this time last year.”