Under the state's controlled border arrangements, travel from those states to WA will not be permitted unless approved under extraordinary circumstances.
Mr McGowan said travellers must be vaccinated with two COVID-19 vaccine doses vaccination and undergo 14 days of hotel quarantine.
"The border changes are based on health advice in light of the rapid growth in cases in both Queensland and South Australia," Mr McGowan said.
"My advice to any Western Australian that has an approved G2G pass and wishes to return home from those jurisdictions is to do so immediately."
The state has recorded one new case of COVID-19, Premier Mark McGowan said.
This case is a 27-year-old man who is a backpacker.
"So far we know he was a close contact of an existing case," Mr McGowan said.
"He shared a bathroom with that person. That man is not vaccinated.
"It is believed he has been infectious in the community, so therefore there are further exposure sites."
Mr McGowan said the details of these exposure sites will be uploaded on the WA Health website.
Mr McGowan said it was "widely acknowledged" at today's emergency National Cabinet meeting that WA is in "a very different position" compared to other states and territories.
"While WA has agreed in principle with the changes to testing and close contacts, these new settings will only be implemented in Western Australia at a later stage," he said.
"To be clear, the settings agreed at National Cabinet today are for jurisdictions with a high caseload environment.
"With thousands of daily cases (in other states), Western Australia is not in that position.
"That is accepted and understood at National Cabinet and therefore WA will continue with our existing testing, isolation and close contact settings for the time being.
"The Premier said if the state needs to move to the national settings, that is what they will do.