The 45-year-old handed himself in to officers on Thursday morning after the 39-year-old woman was struck with a kitchen knife in the neck, head and back outside a Sydney gym the previous afternoon.
The attacker allegedly lay in wait as she left Crunch Fitness at Alexandria, in the city's inner south, and then fled as others intervened.
Police will investigate whether any orders were in place to protect the woman before the attack but detectives said the suspect had a history of domestic violence and had been in a brief relationship with the victim.
The woman was treated by paramedics before being taken to hospital in a serious but stable condition.
Charges are yet to be laid.
Premier Chris Minns said NSW faced an "absolute emergency" with the government examining all options as part of its comprehensive response to a growing domestic violence problem.
Courts made more than 39,000 apprehended domestic violence orders in the past 12 months and the government was investigating how people subject to them were monitored, he said.
Electronic tracking would be investigated but the premier flagged challenges around cost and resourcing.
The state opposition is pushing for electronic monitoring of parolees to be extended to people on bail and making this a presumed condition when they are accused of serious personal violence offences.
A witness said the woman was helped upstairs into the gym, where staff began first-aid. (Sam Lock/AAP PHOTOS)
"Electronic monitoring of offenders is not new ground, it operates successfully in other contexts," shadow attorney-general Alister Henskens said.
Domestic violence perpetrators are almost 33 per cent less likely to reoffend and nearly 20 per cent less likely to breach an order when tracked, according to 2023 Bureau of Crime Statistics and Research data.
"It's not a knee-jerk reaction, rather a commonsense approach to protect women," Mr Henskens said.
Attorney-General Michael Daley said advocates urged cabinet not to rush reforms around bail and electronic monitoring.
"There are instances where it does not work, it does not protect the woman and the woman in question does not feel safe," he said.
"The legislation we bring to the parliament will be modelled, will be costed, will be consulted on, will not be motivated by politics … and it will form a part of a broader package."
The government has announced a $230 million package to address domestic violence through early prevention and education as well as support for women's refuges.
Police believe Wednesday's stabbing was targeted and the man and woman had recently been in a "very short domestic relationship".
Police remained at the scene of the attack on Wednesday night. (Sam Lock/AAP PHOTOS)
Witnesses reported hearing the woman scream as she approached her car.
"It was not a normal scream," one woman said.
"Because of the distance, I wasn't sure what he was trying to do to her ... it looked like he was attacking her or he was trying to rob her."
The witness believed the man was hiding as she did not see him when she arrived.
Another witness saw the woman helped upstairs into the gym, where staff began first aid.
"She ran all the way upstairs, she was bleeding from the neck, from her ears," he said.
Women's Minister Jodie Harrison said it was another terrible incident that should not have happened.
"The status quo needs to change, it's unacceptable, we know that women are exhausted," she said.
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