A damning independent report into the parliament's workplace culture has been described as "sobering, confronting and completely unacceptable" by Premier Dominic Perrottet.
The investigation, conducted by former sex discrimination commissioner Elizabeth Broderick, found one in five people who work in the parliament have experienced sexual harassment in the last five years.
Five people reported an attempted or realised sexual assault, while more than one in four people experienced bullying in the past five years - with several offices identified as "hotspots" for the behaviour.
"Every workplace across our state should be safe from sexual harassment and sexual assault, that is clearly not the case," Mr Perrottet said on Friday.
"Clearly we have a culture in the NSW parliament that over time has become, in many instances, toxic and wrong."
He said the report only marked the beginning of cultural reform at the parliament and pledged to follow through on its recommendations.
They included strengthening internal policies and codes of conduct, reducing alcohol use, boosting support services and monitoring "well-known hotspots" for bullying.
"This must end, it ends today," Mr Perrottet said.
Only one in four people working in the building participated in the report, which involved input from MPs as well as political, cleaning, security and catering staff.
Minister for Women Bronnie Taylor said people who were responsible for some of the behaviour identified in the report should leave the parliament.
"You know who you are, and my very strong advice to you is that you do not belong in the parliament of NSW," she said.
The government says it will work with NSW Labor to act on the report and change the culture in the Macquarie Street building.
Opposition Leader Chris Minns said no side of politics came to the issue with clean hands.
"It really pains a dark picture of what's been happening," he said.
"We all need to better, reach across the aisle, and make sure that we're making every possible effort to make the NSW parliament a safe workplace."
Witness statements in the report portray a workplace where people were too afraid to speak up against bad behaviour, which was more commonly experienced by young staff.
One person said: "It's very normalised, the MP and chief of staff sleeping with junior staff. The power dynamics were so unbalanced."
"It started as flirting. She can't stop it because it would cost her her job," another said.
Others speak of a "real drinking culture" in the building, emotionally taxing working dealing with voters at electoral offices and MPs "disgraceful" treatment of staff.
The independent review was commissioned last year after several complaints were raised about abuse of staff.
Ms Broderick has led 15 cultural reviews into major institutions including NSW Police and the Australian Defence Force.
Mr Perrottet earlier said there was zero tolerance for bullying, days before firing fair trading minister Eleni Petinos on August 1.
Ms Petinos, who was responsible for keeping the state's workplaces safe, last week rejected accusations of bullying linked to her office.
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