Nine of the new cases are linked to an outbreak at a lithium plant in the state's southwest, with 17 infections now found in the greater Bunbury area.
The remainder are from the Perth metropolitan area, including two people who have not been linked to other known cases.
Just 8638 people were tested for COVID-19 on Tuesday, which Premier Mark McGowan conceded was not enough.
But the premier said the chief health officer was confident Wednesday evening's Australia Day Skyworks event could go ahead despite the spread of Omicron.
"I was just in a room wearing a mask with hundreds of people becoming Australian citizens. That's occurring all over Western Australia, these events, and often they're indoors," Mr McGowan told reporters.
"In terms of the Skyworks, the advice we had was we could proceed safely on the basis people wore masks and people used common sense."
The City of Perth last week said attendees would face spot checks for their proof of vaccination and could be asked to leave if they failed to comply.
But the council has since backed down, instead encouraging people to only attend if they are double-vaccinated and feeling well.
The Australian Nursing Federation has called for the fireworks to be cancelled, saying it could become a super-spreader event.
Tens of thousands of attendees have flocked to the banks of the Swan River for the event in previous years.
"I expect the turnout will be down, given what's going on," Mr McGowan said.
"I expect most people will do the right thing, overwhelmingly they will. You have to make these judgment calls and the advice was it was safe to do so."
Thirteen workers have tested positive at Albemarle's Kemerton lithium hydroxide plant, under construction 150 kilometres south of Perth.
Four close contacts have also tested positive, with results pending from 14 close and casual contacts.
Many of those people are believed to have been infectious while in the community and the cluster is expected to grow, WA Health said.
Mr McGowan said one contractor in particular at the Kemerton site had been affected and that work area had been shut down.
Australian Manufacturing Workers Union state secretary Steve McCartney said workers feared they would contract the virus and take it home to their families.
"They are being driven to site on crowded buses from accommodation, there has been no visible increase in cleaning and no instigation of split shifts or staggered breaks," he said.
"Some contractors are telling their employees some information, and others have been completely mum. They all need to work with unions onsite and health and safety representatives to get this right."
An Albemarle spokesman said all workers at Kemerton were vaccinated and the site was adhering to WA Health protocols.
WA's double-dose vaccination rate has now reached 90 per cent, a threshold that was meant to trigger the reopening of borders from February 5 before Mr McGowan backtracked on the plan.
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