The average UK household had £174 a week left after paying the bills in September, which is £6 more than they had the same time last year.
The weekly sum revealed by Asda was on a par with the highest previously recorded back in January 2010 and marked the 12th month in a row that families' spending power had grown.
Regionally speaking, London, the East Midlands and Yorkshire and Humber saw the biggest increases in 'discretionary income' (the money left after spending on essentials such as rent, utilities and bills) - enjoying £10, £8 and £7 more a week than last year respectively.
Reductions in the price of fuel and food were largely to thank for that bit extra left over, having fallen by 6% and 1.4% respectively over the year.
Other more recent price cuts that helped too included flights and sea fares, which fell by 21.7% and 18.8% between August and September and a bigger reduction compared to the previous year's change.
Wider economic factors have been improving the fortunes of the typical household with consumer price inflation now at 1.2%, its lowest level since the end of the recession in September 2009, and a reduction in unemployment.
Andy Clarke, president and chief executive of Asda, said: "This time last year I said there needed to be action to address serious disparities in regional incomes. Twelve months on I am pleased to see that disparities across the regions are narrowing and household budgets across the UK are enjoying continued national growth. Inflation is slowing, food price inflation is falling each month and with unemployment at an all-time low, families across the UK have more pounds in their pockets."
Rob Harbron, senior economist at the Centre for Economics and Business Research, added: "It is encouraging to see family spending power rise once again, moving back towards the year-on-year increases seen in the first quarter of this year."
"Falling prices in key sections of household budgets, namely food and vehicle fuels, have helped take inflation on the cost of living to its lowest level since the end of 2009, relieving pressure on household finances. With important global commodity prices continuing to weaken, continued easing of price pressures is likely to lead to further improvements in discretionary income in coming months."