The data collected by social media monitoring firm Social Bakers showed that the network's monthly active Australian users fell from about 11.8 million in December to just over 11.5 million in the past week, News.com.au reported.
It revealed that about 115,000 less people are logging on to Facebook each month since the new year, with the network losing about 390,000 active users overall.
The figures were collated from Facebook's publicly accessible ad tools, used by marketers and developers to determine audience reach.
Social media marketing expert at the Queensland University of Technology Business School, Professor Larry Neale, said there had also been a decline in Facebook users in North America and Europe, as "Facebook fatigue" sweeps the globe.
"When Facebook was starting up they got a lot of people on and it was very novel, but the novelty has worn off a little bit, so now people are scaling back use," he said.
Prof Neale said the decline could also be attributed to Facebook members of three or more years drifting away from the network as they discover they no longer have time for it.
Adelaide social media consultant Michelle Prak said while more than half the population now owns a Facebook account, the network's ban on members under 13 coupled with older people's general lack of interest in it means it may have reached a stalemate in Australia, with no real potential to grow user numbers any further.
Prak said boredom, a desire to try new technologies and frustration with Facebook's ever increasing use of advertising were helping to drive users away from the network.
QUT social media researcher Dr Christine Satchell said the proliferation of more "open" social media channels, such as link sharing site Reddit, were contributing to users' migration away from Facebook.
Facebook fatigue isn't a new phenomenon. In 2011, millions of users in the US and Europe began deactivating their accounts and there were predictions the same would happen in Australia.