Some families have been waiting up to 10 years to secure an affordable home as the social housing waitlist blows out to nearly 60,000.
Yet this figure shows only part of the picture, with an estimated 144,000 people likely in need of social housing, says a researcher after analysing census data.
Hal Pawson, from the City Futures Research Centre at the University of NSW, said the dire wait times meant some dropped off before they could receive housing while others didn't bother applying.
"The scale of housing need is actually a lot larger than the social housing wait list shows," he told a housing forum on Thursday.
While the private market could help if federal rental assistance increased, private tenancies are "much less secure" housing.
Professor Pawson said increasing the stock of social housing, which has fallen behind NSW's population growth, was necessary.
The inner city suburbs of Erskineville, Beaconsfield and Zetland are among the places where wait times for anything larger than a one-bedroom unit is 10-plus years.
Sydney Lord Mayor Clover Moore told the forum this is "truly devastating", and asked:Â "What are they going to do in that decade?"
Pointing to those sleeping rough, she called for an immediate resumption of the temporary accommodation and private rental assistance packages set up in the early days of the COVID-19 pandemic.
For $34 million, about 13,000 people were housed for three months
"If we were able to ensure every person in Sydney had accommodation during COVID, we should be able to do it now," Ms Moore said.
The social housing waitlist jumping from 49,928 to 57,750 should be a wake-up call to every politician in the state, the Community Housing Industry Association NSW said.
"You cannot continue to sit idly by while tens of thousands of everyday families and individuals struggle for the basic necessity of housing," the association's CEO Mark Degotardi said.
"We've had years of neglect by both sides of politics.
"This emergency will be hard to solve, and we must start now. Investment in social and affordable housing delivered by community housing providers is the key."
Premier Dominic Perrottet said there were 30,000 fewer people on the social housing waitlist than under the Labor government, which lost power in 2011.
"Now, I don't want anyone on the waiting list. That's why we're building more homes," he told reporters.
His government would address short-term and long-term economic issues, he said.
Opposition housing and homelessness spokeswoman Rose Jackson said Labor would increase social housing stock and mandate affordable housing requirements for new developments, if elected in March.