Regional Express says it will mandate the use of face masks for all passengers as an extra layer of protection against the spread of COVID-19.
Face masks will be made compulsory on all Rex flights from June 1, 2020.
Passengers are to use their own masks and those without masks can purchase one at check-in.
The airline says that passengers will be denied boarding if they refuse to wear a mask except if there are exceptional reasons.
Passengers must wear masks at Rex check-in counters (or worn immediately after purchasing from a check-in counter), at boarding gates, during tarmac transfer both at boarding and disembarkation (including during bus transfers), and on-board the aircraft.
Rex's national airports manager David Brooksby said they needed to be vigilant to prevent a second wave of infections which would cause untold economic damage and misery.
"The health and safety of passengers and employees is paramount and we thank our passengers for putting up with the inconvenience as an act of consideration for our staff and other passengers," Mr Brooksby said.
"Rex has already enforced significant changes to minimise the risk of infection, including the proactive and unprecedented measure of body temperature testing of passengers and employees," he said.
"Since early March, Rex has endeavoured to space out seating allocation of all passengers to facilitate social distancing.
"Unrelated parties will not be assigned seats next to each other when and where possible."
In April, Rex started testing temperatures for both passengers and staff before they boarded planes or began their shifts in a bid to protect people travelling with the airline.
Regional Express operates three flights a week from Sydney to Griffith and Narrandera airports with federal government funding support.