Research from Kantar Worldpanel has shown market shares in the discount supermarket to increase in the 12 weeks to August 14 by a record 5.2 percent.
Sales were also strongest among families with children, with its sales among this group growing 40% faster than among non-children households.
Aldi was not far behind with sales growth of 17.2%, attracting 1.1 million more shoppers than this time a year ago and increasing market share to 7%.
The rise means Lidl has overtaken posh supermarket Waitrose as the seventh largest supermarket in Britain. The business is going from strength to strength, supported by our efficient model and hard-working employees.
The first British Lidl opened in 1994 and it now has more than 650 stores nationwide after an ambitious expansion programme.
Aldi, the other German discounter that is closely associated with Lidl, also performed well in the period.
Overall sales grew by 3.0% at Tesco, helped by an increase in volume sales, but market share fell to 27.8% - down 0.3 percentage points compared to a year ago. Inflation is now running at 2.6% in the United Kingdom and forecast to peak at around 3% later this year.
Meanwhile, shoppers saw a further squeeze from higher prices, with grocery inflation ticking up to 3.3%, compared to 3.2% the month before.
Shares in Tesco were up 2.7 percent this morning.
Asda's market share slipped to 15.3%, from 15.7% for the comparable 12 weeks, and Wm Morrison Supermarkets' share dropped to 10.4%, from 10.6%.
The "big four" - Tesco, Sainsbury's Asda and Morrisons - all increased sales for the fifth period in a row, their best performance since 2013, but nevertheless lost market share as the discounters grew much faster. "Ice cream sales were down 9% as consumers huddled indoors, while sales of burgers slumped by 25% - an £8 million loss year on year - as rain dampened the nation's appetite for barbecues".