All arrivals from Victoria into New South Wales will be subject to 14 days of hotel quarantine.
Residents will only be able to return to the state via Sydney Airport from midnight on Thursday, unless they reside within the NSW border regions.
As the arrivals abroad, they will be required to stay at their own expense in a government-run hotel quarantine.
Premier Gladys Berejiklian said the new line of protection would help minimise the likelihood that the virus would spread throughout the state.
Border permits are also to be further limited.
Anyone who has been in Victoria for the past 14 days is barred from entering New South Wales under the Public Safety (COVID-19 Border Control) amendment without a border permit.
‘We love our Victorian fellow citizens, but their rates of infection are incredibly high at the moment and not going down,’ Ms Berejiklian.
‘We are reviewing and look to tightening some of those definitions to make sure only those with absolutely necessary requirements [are allowed to enter],’ she said.
There would be some exemptions, she said.