On June 17, one of the longest nights of the year, leaders in business, community and government will spend the night without shelter for the annual Vinnies CEO sleep out.

About 1500 people are expected to participate in the event, which Vinnies hopes will raise $7.9 million.

Organisers were forced to adapt last year with COVID-19 restrictions prohibiting large gatherings.

Participants instead slept in their backyards, cars or on their couches, raising $5.7 million for the organisation.

With homelessness again beginning to grow towards the "appalling" rates seen before the pandemic, St Vincent de Paul NSW CEO Jack de Groot says the event has never been more important.

"During the pandemic, the political will was found to provide temporary accommodation for many rough sleepers in NSW and around the country," he de Groot said.

"No-one can now say we don't know what to do, to at least significantly lessen the numbers of people rough sleeping - we've only recently witnessed an effective solution in action."

Only about a quarter of those for whom accommodation was found during the pandemic have been provided with longer term housing.

At the most recent count, NSW is home to at least 1100 rough sleepers.

St Vincent de Paul NSW President Peter McNamara encouraged the public to give generously.

"There's no excuse at all to return to the, frankly, appalling rates of rough sleeping that seemed intractable before COVID," he said.

"We've seen a more compassionate Australia during the pandemic and there is every reason why we can all work to see this continue," Mr McNamara said.

The money raised will go to services who provide rough sleepers with emergency accommodation, food and water, clothes, blankets, and more.

Australian Associated Press