Police will not need a warrant or suspicion before using metal-detecting wands on random individuals under the NSW measures, which came into effect on Monday.
But the hassle of people being searched would be worth it if the measure saved lives, Premier Chris Minns said.
Authorities hope random knife searches will stop people from carrying them in the first place. (Dean Lewins/AAP PHOTOS)
Much like roadside breath testing, the premier said a random approach to where the searches would occur would keep prospective criminals on their toes.
"There will be inconvenience for members of the public, but we believe it's a small price to pay to keep people safe … the sad reality is that when it comes to a weapon, knives are the most likely reason someone will be killed in NSW," he said.
"This is not everywhere and all the time, but what this does, by its randomness, (it) hopefully means an individual doesn't take a knife out in the first place or doesn't purchase a knife."
Senior police can declare a designated area allowing officers to scan people for 12 hours in an area where knife- or weapons-related violence has taken place in the past 12 months.
The wanding laws align NSW with Queensland, the Northern Territory and Western Australia. (Dean Lewins/AAP PHOTOS)
"Regrettably, the truth is that covers many places in metropolitan Sydney ... mainly major infrastructure, transport hubs, shopping centres and other places where people congregate," Mr Minns said.
The laws came after a spate of high-profile knife incidents in Sydney, including the Bondi Junction shopping centre attack in April that resulted in six people being stabbed to death.
The changes have been criticised for being likely to disproportionately impact some communities and subject people to possible surveillance or harassment.
When the laws passed parliament, NSW Council for Civil Liberties president Lydia Shelly pointed out knife crime had consistently trended down over the past two decades.
There were 4258 violent knife incidents recorded in 2004 compared with 1518 in 2023, according to the NSW Bureau of Crime Statistics and Research.
"There is simply no evidence supporting the introduction of these laws ... proactive policing does not serve as a deterrent for crime, nor does criminalisation and increased penalties," Ms Shelly said at the time.
Premier Chris Minns says the inconvenience to some will be a small price to pay to boost safety. (Dean Lewins/AAP PHOTOS)
But Police Minister Yasmin Catley said the laws were designed to spark a cultural change that stopped people arming themselves in the first place.
"We want to say to young people, 'do not go out with a knife in your back pocket'," she said.
"It's dangerous, it's devastating, and we know this legislation is definitely going to have that impact."
The NSW government also recently doubled penalties for knife possession to a maximum of four years in prison.
The wanding laws align NSW with Queensland, the Northern Territory and Western Australia, all of which have announced or rolled out similar powers for police.