Imports by the world's top consumer have now risen for three consecutive months, with the third quarter recording the best quarter of the year for overseas purchases.
China's appetite for gold has improved in the second half of 2015, as domestic stock markets performed badly.
Its net gold imports from Hong Kong rose to 97.242 tonnes last month from 59.319 tonnes in August, according to data emailed to Reuters by the Hong Kong Census and Statistics Department.
September's imports were the highest monthly overseas purchases since November 2014.
The robust numbers came in the lead up to a seasonally strong fourth quarter.
China's peak season for gold demand kicked off from the national day holiday in the first week of October. It lasts until the Lunar New Year early next year as gold is a popular choice for gift giving.
Imports have also been boosted by higher premiums as banks can make a good profit from the difference between global and Chinese gold prices, traders have said.
China's gold demand in the second half of the year will be better than the first half, due in part to falling stock markets, GFMS analysts at Thomson Reuters said earlier on Tuesday in the third-quarter update of their Gold Survey 2015.
"Having said that, we still expect China's total gold demand to record a second consecutive annual decline in 2015," GFMS said.
Chinese demand hit in a record high in 2013, when gold prices slumped following a 12-year rally, but consumption has eased since that buying frenzy.
China does not provide official trade data on gold, so the Hong Kong figures serve as a proxy for flows to the mainland.
The Hong Kong data, however, does not provide a full picture of Chinese purchases as imports also come directly through Shanghai and Beijing.