NSW is second only to Nevada, home to casino-lined Las Vegas, when it comes to the number of gaming machines with nearly 90,000 across the state.
More than 670 pubs and clubs will be mandated to shut down all poker machines between 4am and 10am each day.
The venues had been able to bypass the shutdown period via a decades-old loophole that let the state government grant exemptions to businesses claiming financial hardship.
Gaming Minister David Harris said the variations to a 2001 law were no longer fit for purpose for pubs and clubs, echoing recommendations of an independent report into electronic gaming machines handed to the government more than a year ago.
Operators have been given until March 31 to implement the changes.
Mr Harris denied the government was slow to move on the report, given the longstanding loophole.
"They were given those exemptions, some of them 20 years ago, some of them for hardship which clearly isn't the case now," he said.
"These are businesses and you can't just jump in and just cut them off at the throat."
The state government has also baked continued gambling losses into its financial plans.
Its most recent budget showed it raked in $2.3 billion in tax revenue, a figure it has forecast to increase to $2.9 billion by 2027/28.
Greens MP Cate Faehrmann said enforcing the shutdown period was "the absolute bare minimum" the government should be doing.
"Shutting down this loophole should have never taken this long ... this exemption has been exploited for years by venues chasing every last dollar of gambling harm," she told AAP.
A 2023 report into electronic gaming machines showed 70.5 per cent of gamblers were classified at high or moderate risk between 4am and 10am.
"Vulnerable communities exposed to the growing social and economic costs of problem gambling will now have a buffer where these venues will close their gaming rooms," NSW Council of Social Service CEO Cara Varian said.
A Grattan Institute analysis estimated NSW residents lost $1288 per adult on pokies in 2023, double the average of other states.
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