Seasonally adjusted gross domestic product (GDP) rose by 0.8 percent on the quarter, the data showed. This was stronger than the consensus forecast of 0.6 percent in a Reuters poll and marked an increase from the 0.6 percent in the second quarter.
The economy grew by 2.3 percent on the year in the third quarter, unadjusted data showed. This was in line with a consensus forecast.
Adjusted for calendar affects, the yearly growth rate rose to 2.8 percent in the July-September period from 2.3 percent in the previous quarter, the office said. This was the strongest reading since the beginning of 2014.
The figures give Chancellor Angela Merkel a tailwind as her conservative bloc tries to forge a tricky three-way coalition government with the pro-business Free Democrats (FDP) and the left-leaning Greens, an alliance untested on a national level.