Inflation stood at 12.2% in England, 4.7% in Wales, 6.7% in Scotland and 9.6% in Northern Ireland.
Prices paid by first-time buyers were 12.9% higher year-on-year, while owner-occupiers paid 11.2% more.
On a seasonally adjusted basis house prices increased by 0.6% between July and August.
David Newnes, director of Reeds Rains and Your Move estate agents, said: “While price growth dulls, activity in the market is still vibrant, and total house sales completions are up 16% year-on-year in September.
“First-time buyers have been bringing much of the vitality and optimism to the party.
“While the market adapts to a mellower beat, schemes like Help to Buy and an accessible lending environment are essential to ensure that confidence isn’t silenced, and activity continues to sing.”
Excluding London and the South East, where property prices increased by 19.6% and 12.3% respectively, UK house prices inflated by just 7.8% annually.
In the North average prices stand 8.3% (£13,400) below March 2008 levels, while London’s prices are 47.3% above February 2008 levels, when they previously peaked.
Newnes added: “A North/South divide in the field remains evident in the race back from the debris of the financial crash. For six regions of the UK, average property prices achieved on completion are yet to match their pre-crisis score.
“The path of the London property scene is best plotted on a different scale to the rest of the country.
“However, the rate of annual house price inflation in the capital eased in August, as we see growth relaxing into a slower tempo from the heady pulse earlier this year.”