The overall number of people with a job increased by 5,600 on seasonally adjusted estimates, figures from the Australian Bureau of Statistics showed, but the participation rate dipped 0.3 per cent from August to 65.4 per cent.
Economists had forecast that both the unemployment and participation rates would remain steady.
The last time the seasonally adjusted unemployment rate was this low was June 2011, at 4.9 per cent.
The Australian dollar, which had been as low as 71.05 US cents on Thursday, spiked from 71.12 to 71.28 US cents on the data's release.
