A report by Lloyds TSB says last year's figure is lower than at any point since 1998, when the home and garden improvement frenzy was at its height.
Lloyds TSB said total expenditure on home maintenance - combining DIY and trade services - had fallen by 9% last yea from £17.8bn in 2009 to £16.2bn in 2010.
The amount spent on trade provided services fell by 3% over this period, from £6.9bn to £6.7bn.
Suren Thiru, a housing economist at Lloyds TSB, believes the DIY downturn is temporary and Britons will rediscover their passion for it when the economy improves. "The current squeeze on household finances from high inflation and weak earnings growth has made it difficult for many households to spend as much as they used to on discretionary items such as home maintenance," he said.
But the benefits of "maintaining or improving your property are likely to ensure that, over the long term, the popularity of DIY will remain enduring".
The decline was one of the factors in the failure of the Focus DIY chain, which collapsed in May with the closure of 120 outlets and the loss of 3,000 jobs.
The DIY sector has been among the hardest hit as the housing market, one of the most important forces behind spending on home improvements, collapsed.
One of the administrators appointed to oversee the winding up of Focus, Simon Allport of Ernst & Young, said: "UK retailers are facing one of the most challenging retail environments in recent times and the DIY sector has become highly competitive, with only the strongest players being able to thrive and survive."