Today's figures - aided by a rebound in consumer spending and investment in new home-building - unofficially ended the worst US recession in 70 years.
The Commerce Department, in its first estimate, said the economy grew at a 3.5% annual rate, the fastest pace since the third quarter of 2007, after contracting 0.7% in the April-June period.
The growth pace was above market expectations for a 3.3% rate.
The economy last grew in the second quarter of 2008.
Recessions in the US are dated by the National Bureau of Economic Research and the private-sector group often takes months to make determinations.
The economy slipped into recession at the end of 2007 and has been in the worst downturn since the Great Depression of the 1930s.
The recovery was generally broad-based, with solid gains in consumer spending, exports and investment in home-building.
Consumer spending, which accounts for over two-thirds of US economic activity, surged at a 3.4% rate in the third quarter, the fastest pace since the first quarter of 2007.
Residential investment, which was the main force behind the downturn, jumped at a 23.4% annual rate in the third quarter, contributing to GDP for the first time since 2005, after declining 23.3% in the April-June period.
The surge in consumer spending and residential investment was likely to have been driven by government stimulus programmes.
