Sydney is closing in on the population milestone of 5 million residents, according to the 2016 Census results released on Tuesday.
But south of the border, Melbourne is growing at a faster rate - 12 per cent over the past five years compared to 10 per cent for Sydney.
Melbourne's population is 4.4 million, and now trails Sydney by around 400,000 residents.
Sydney remains Australia's largest population centre with 4,823,991 people, growing at 1656 every week since the previous Census.
Australia's estimated population at December 31 was 23.4 million people.
There were 23,717,421 people in Australia on Census night, which included 23,401,892 people who usually live in Australia - an 8.8 per cent increase from 2011. More than 600,000 Australians were travelling overseas.
NSW remains our most populous state, with 7,480,228 people counted, ahead of Victoria (5,926,624) and Queensland (4,703,193).
The Australian Capital Territory experienced the largest population growth of any state or territory over the past five years, adding more than 40,000 new residents - an increase of 11 per cent.
Australians are getting older with 664,473 additional people aged 65 and over since 2011.