An informal "street count" by staff of City of Sydney council and volunteers has identified 486 homeless people sleeping rough in the inner city, the highest figure since the initiative was launched in 2010.
"This is a tragic situation and I am deeply saddened by the dramatic rise in numbers," Lord Mayor Clover Moore said in a statement.
"We all know Sydney is in the grip of a housing crisis, and now even middle-income earners are finding it tough to pay their rents and mortgages," she said.
Declining housing affordability was contributing to the high numbers of homeless people identified by the count, which was almost 25 percent higher than last year.
According to council figures, Sydney's mean rental prices have jumped almost 60 percent since 2006 while household incomes have grown by 48 percent.
It estimated that 84 percent of low-income households in the council's jurisdiction are paying 30 percent of their gross income on housing.
A report on Friday showed mental illness and substance abuse are rife within the homeless community.