Two men in their 80s have died, bringing the total deaths in the state to 29 and upping the national toll to 113.
Among Thursday's new cases, 28 are linked to known outbreaks while 289 cases are under investigation, Premier Daniel Andrews said on Thursday.
There are 2128 active cases in the state.
"Everyone would prefer this to be a very different set of circumstances but it's not an ordinary winter," Mr Andrews warned.
"This is not an ordinary week. If we pretend it is, if we pretend it is over because we want it to be over, all we'll be doing is spreading the virus, seeing more people in hospital and sadly more people will pass away as a result of this virus."
More time is needed for the numbers to stabilise and drop, given the fresh stay-at-home orders for metropolitan Melbourne and Mitchell Shire are just a week old, Mr Andrews said.
The 317 new cases recorded in the state make it the 11th consecutive day of a triple-digit increase in Victoria.
Of those, 109 people are in hospital with 29 in intensive care.
The previous national daily record was Victoria's 288 last Friday.
Victoria has had a total 4750 confirmed cases since the pandemic began.
About 28,000 people in Victoria were tested for the virus on Wednesday.
"It's a massive and powerful contribution to our fight against the virus," Mr Andrews said.
"You can't contain this if you don't know where it is."
The state government has also paused all category three elective surgeries - including hip and knee operations - at Melbourne health services to make sure extra beds are available for the virus surge.
Meanwhile, about 140 police officers are quarantining after coming into contact with people infected with coronavirus.
Victoria Police Chief Commissioner Shane Patton confirmed those officers and 30 protective service officers are off the beat due to the state's latest outbreak.
"It's a concern for us, there's no doubt about that," he told 3AW radio on Thursday.
Last Friday, health authorities in Victoria encouraged people in locked-down metropolitan Melbourne and the Mitchell Shire to wear masks when social distancing wasn't possible.
Since then, mandatory use of masks was imposed on health workers at aged care facilities and home care providers across Victoria's locked-down areas.
Victoria Police on Wednesday recommended its officers wear masks within their stations, including where no contact with the public occurs.
People will also be expected to wear masks in the state's courts, where disposable masks will be available at entrances before security checks.
