The "significant public health issue" of loneliness will be placed under the microscope, with a NSW parliamentary probe to delve into what is seen as an escalating problem.

The upper house inquiry will look at the extent, causes and impacts of loneliness and review how other jurisdictions are tacking it.

It will also seek to identify those most at risk of social isolation and explore the best steps to reduce loneliness.

Official estimates suggest about 40 per cent of NSW residents experience loneliness, which has been linked to premature death, poor physical and mental health and psychological distress.

In Sydney, a city of some five million people, there are 1.7 million residents living alone or currently single who are considered at risk from loneliness.

Mental Health Minister Rose Jackson said the inquiry would help the government better understand the issue.

"We aim to delve deeper into loneliness, which has emerged as a significant public health issue following the COVID-19 pandemic," Ms Jackson said on Monday in a statement.

"This inquiry shows our political leaders are sitting up, taking notice and want action to support people who might be struggling."

Relationships Australia NSW chief executive Elisabeth Shaw said the impacts of loneliness could be life threatening.

"Loneliness is an experience we all have from time to time. When it becomes chronic is can lead to further impoverishment in terms of identity, life experience, confidence, and can even shorten your lifespan," Ms Shaw said.

"We vary in how much human contact we need but we all need others to survive and thrive, emotionally and physically."

The inquiry, chaired by Labor MP Sarah Kaine, is set to hold public hearings in November.