The premier, who indicated the extension earlier this week, said he was making an official directive.
Andrews said there would be spot checks on businesses potentially breaking those rules and that staff could even ring up and dob in their employers for making them work from the office.
“There is no option but to do this,” Andrews said, adding it was one of his “most significant concerns”.
“If you have been working from home you must keep working from home,” he said.
“It’s critically important to avoiding a second wave.
“We can’t switch back to normal… we’ve got to find a COVID normal.
“If everybody tries to go back to office blocks we will simply have too many people in too close a contact… that will potentially lead to a second wave.”
The premier said public transport in Victoria can only be used at a capacity of 15 per cent due to social distancing rules.
But he also noted that if people drove it could cause “absolute traffic chaos”.
It comes as Victorians prepare to have a little more freedom from next Monday, June 1, with indoor and outdoor gatherings of up to 20 people to be allowed, along with regional travel and the reopening of restaurants, cafes, libraries and beauty salons, provided they adhere to limits on numbers and practise social distancing.
Follow the link for a full list of the restrictions to be eased in Victoria from June 1.