The rental vacancy rate for December was just 0.7 per cent in Perth and even lower in some regional areas, according to the Real Estate Institute of WA.
WA's public housing waitlist has meanwhile blown out to more than 18,000 applications as a shortage of tradies and materials stalls the construction of new properties.
The state will reopen its borders from February 5, with the relocation of skilled workers from the eastern states and overseas expected to drive rental costs even higher.
Shelter WA chief executive Michelle Mackenzie fears the market constraints will lead to more people couch-surfing and sleeping rough.
"What we're finding already is that so many people are paying more and more of their income on their rent given the constraints of the market," she told AAP.
"It means that they're going without other basic necessities just so they can pay that rent.
"We're reaching kind of a perfect storm of new people needing homes, not enough homes for the entire population, so where are people going to live? There are suburbs that have just got no affordable rentals at all - in particular in regional WA, that's really concerning - so we are acutely worried."
Thousands of apartment developments have been put on hold in recent months amid soaring construction costs, according to the Property Council of Australia.
Industry forecasts suggest supply issues are unlikely to be eased until the end of the year or early 2023, when about 10,000 more rental properties are expected to become available.
The McGowan government committed an additional $884 million towards social housing and homelessness in the September budget but has also struggled with trade shortages.
"It's terrific that the government has (committed) new money, they just can't deliver on the promise that was in the budget because there's not enough tradies to do the work," Ms Mackenzie said.
Advocates hope a pending review of WA's tenancy laws will provide renters with greater security and are calling for parties to address housing affordability at the federal election.
Shelter WA met on Tuesday with homeless service providers and WA's health and communities departments to update the state's COVID-19 rough sleeper response plan.
Service providers are particularly worried about the impact of staff being unavailable to work after being exposed to the virus.
Ms Mackenzie said there was a strong argument for reopening the borders in a phased approach to prevent an overwhelming surge in cases.
She said the key lesson from early in the pandemic was having clear delegation between stakeholders and flexibility in resourcing.
"We do know that people who are sleeping rough have got very, very low vaccination rates so that's a huge concern," she said.
"They also have higher comorbidity rates, so they're much more likely to get COVID.
"It's really scary, but at least we know the date the borders are opening and we're working really hard to have plans in place to address this."
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