Victoria reported 191 new COVID-19 cases overnight – the biggest rise since the epidemic began.
The state reported its previous high of 127 new cases on Monday.
The restrictions will become effective on Wednesday night and be in place for six weeks.
The decision to enforce this lockdown marks the first time the border between Victoria and New South Wales has been shut in 100 years.
Movement between the two states was last blocked in 1919 during the Spanish flu pandemic.
Premier Daniel Andrews said in a media briefing in the city: “These are unsustainably high numbers of new cases.
“It is the smart call, the right call at this time, given the significant challenges we face in containing this virus
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