Consumers spent more last month as they started their early Christmas shopping and spruced up their homes, according to new figures.
The latest BRC-KPMG Retail Sales Monitor showed that total sales increased by 5.6% in September.
Separate consumer spending figures from Barclaycard showed a 2% increase, representing the strongest improvement in credit card spending since February, before the pandemic fully hit.
Helen Dickinson, chief executive of the British Retail Consortium (BRC), said: "September saw a big improvement in retail sales growth, however sales over the last six months are still down on the previous year."
The BRC-KPMG report revealed the strongest monthly sales growth for retailers since December 2009, as like-for-like UK retail sales grew by 6.1%.
Nevertheless, sales of non-food items fell by 12.3% in stores for the quarter to the end of September as the high street's post-virus recovery continues.
Total non-food retail sales increased by 5.2% as shoppers bought more clothing and homeware online over the three-month period.
Ms Dickinson added: "Tighter coronavirus restrictions have continued to hold back clothing and footwear, particularly as the Government further restricts social events.
"With office workers still at home for the foreseeable future, the sales of electronics, household goods and home office products have remained high.
"September sales have also given retailers early signs that consumers are starting their Christmas shopping earlier this year, which retailers are encouraging their customers to do in order to manage demand at Christmas and keep people safe."
The figures also revealed that food sales increased by 5.6% over the three-month period to the end of last month.
Barclaycard's latest consumer spending data for September also showed that food spending was particularly strong last month, as shoppers stocked up on more essentials amid concerns over tightening lockdown restrictions.
It reported that spending on essential items increased by 6.1%, driven by a 15.4% lift in supermarket shopping.
The figures also revealed a 4.2% increase on the amount being spent on clothes as shoppers bought more items online during the month.
Spending in bars and pubs also lifted during the month, moving 9% higher, while restaurants saw spending sink by 18.7% following the end of the Eat Out to Help Out scheme.
Raheel Ahmed, head of consumer products at Barclaycard, said: "Consumers clearly made the most of the sunshine by socialising in September, with spending at pubs and bars seeing the first increase since before the national lockdown was introduced in March.
"However, we also saw households preparing to spend more time inside as winter draws closer, with home improvement increasing as a result.
"While the nation's confidence in the UK economy has improved slightly, many are still cautious about the upcoming winter months, and the subsequent uncertainty it may bring has caused some to start stockpiling once more."
