A hard border will split metropolitan Victoria from regional areas as the state seeks to limit the spread of the virus outbreak.
Victorian Premier Dan Andrews said the border will separate 31 locked-down metropolitan local government areas and the Mitchell Shire from regional areas.
"No one is pleased to be in that predicament, to having to confront those circumstances, but there is enormous benefit across regional Victoria if we can get that job done," Mr Andrews said.
Victoria Police Chief Commissioner Shane Patton said hundreds of police officers will be checking people had a valid reason for leaving locked-down metro areas.
A focus will be on main arterial roads such as the Hume Freeway that leads to regions such as Calder, Geelong and Gippsland.
"It won't be an absolute ring of steel, but there will be a significant police presence," he said.
"We're going to be there from midnight tonight. We're going to be checking people. We're going to be making sure they're adhering to those guidelines. If you don't have a reason to leave, you will be turned back around. If someone breaches those guidelines and leaves when they shouldn't, you'll receive an infringement – $1,652."
FURY OVER STATE BORDER 'DISGRACE'
NSW's top cop has hit back at accusations the process at border checkpoints was a "disgrace" as the NSW-Victoria shutdown faces a chaotic first day.
Cars backed up at cross points as the border closure went into effect at midnight and commuters are facing long delays trying to get into NSW as cars are stopped and checked for the necessary permit to cross.
This chaos has been exacerbated by the return to lockdown happening during local school holidays, with pupils not expected to return until July 13.
Albury Mayor Kevin Mack told 2GB's Ben Fordham the delays this morning were a "disgrace" as people tried to get to work across the border.
"This is not Sydney, this is Albury-Wodonga and people just aren't being treated like they should be treated here," he said.
"We're not going to put up with this for a week, this is just horrendous."
NSW Police Commissioner Mick Fuller told Fordham he was happy with the operation so far.
"I think it's ridiculous to come out day one on such a large border operation and make complaints," he said.
"Perhaps he needs to go down and talk to the police who have been working through the night in freezing conditions, protecting the health of the people of NSW.
"It's not a time to be selfish."
Overnight, queues of cars lined up at the border were stopped and searched by police and army troops as the historic border shutdown went into effect, cutting off the entire state of Victoria.
Motorists are facing significant delays this morning, with drivers spending almost an hour in traffic for what is usually a five-minute trip across the border.
Most of the drivers are Victorian workers trying to get to work via Albury.
It took as many as 12 minutes for cars to cross the bridge into the border town of Moama after being checked by police this morning, the Herald Sun reported.
It was also a difficult night for people trying to apply for a COVID-19 border entry permit into NSW, who were left frustrated as the NSW government website "kept crashing" and went down after its launch, hours before the state line was closed.
Some users were able to click on a red button labelled "Apply Online", which disappeared and reappeared throughout the night, while others were told: "This transaction is not available at this time. Try again later."
It went live about 7.30pm with a number of problems reported in the 20 to 40 minutes that followed.
One woman took to Twitter after her computer screen displayed a message on the site reading: "Sorry, we were unable to process your request".
In a statement to news.com.au on Tuesday night, a Service NSW spokesman said the application system was live "and experiencing high levels of demand".
"We are aware that some people have experienced delays in securing a permit and we apologise for the delay.
"In the interim, travellers will be able to demonstrate their eligibility to cross the border to police by carrying relevant documentation based on a category of exemption."
From 12.01am on Wednesday, July 8, no one can enter NSW from Victoria unless they meet exemption criteria and have been granted a COVID-19 NSW border entry permit.
Applications can be made on the Service NSW website, which went live on Tuesday night.
"Both adults and children are required to get a permit to travel from Victoria to NSW," the state government says.
"The permit is valid for 14 days from the date of issue and applies to all borders: land, air and sea, as well as river crossings.
"Your permit will indicate if you need to self-isolate for 14 days, get tested for COVID-19 or any other conditions."
Those exempt are emergency or law enforcement services workers and anyone entering NSW "to avoid injury or escape a risk of harm".
NSW Health Minister Brad Hazzard said the border closure was "unfortunately necessary to minimise the risk to NSW residents from COVID-19 challenges in Victoria".
NSW Police said fines apply to those who breach the state's public health orders or who falsify information when applying for exemptions.