Authorities confirmed 21 new deaths from COVID-19 in the Oceanic country, all of which were in the state of Victoria, taking the national death toll to 352 and Victoria's to 267. Victorian authorities said the deaths were all among people over 70, with 16 linked to outbreaks in aged care facilities.
Australia has now recorded its deadliest day of the pandemic on four consecutive days and surpassed the previous highest daily number of 19.
The Australian government deputy chief medical officer, Nick Coatsworth, said in an update in Canberra on Wednesday that there had been 22,127 cases in the country, and the number of new cases in the last 24 hours is 428.
Of the new cases, 410 were also reported in Victoria, ending a run of three consecutive days with new infections below 400. The other 18 cases were confirmed in New South Wales, the Oceanic country's most populous state.
Residents in Victoria are under various levels of lockdown as it struggles to contain an outbreak that has, for weeks, seen hundreds of new cases confirmed every day.
In central Melbourne, Victoria's state capital and Australia's second-largest city, people who are not essential workers may leave their houses only to grocery shop or exercise for an hour. There is a curfew in place from 8 pm to 5 am.