Danny Zayak was arrested after Tatiana Dokhotaru's body was found in a Liverpool unit block on Saturday night nearly a day after an anonymous triple-zero call reported an alleged domestic violence dispute.
The 28-year-old has been charged with 18 separate counts, including assault, stalking, choking without consent, and contravening an apprehensive violence order. He has not been charged over Dokhotaru's death.
Assistant Commissioner Stuart Smith said further charges could not be ruled out.
Police had traced the midnight call to the unit block but could not find the apartment where the incident had occurred when they arrived about 3am.
The distressed caller did not specify her address.
About 8pm Saturday, police were called back to the Liverpool unit block, where they found the 34-year-old's body.
Inquiries into who had made the phone call continued throughout Saturday, police said.
The 20-hour gap between the anonymous triple-zero call and the discovery of Dokhotaru's body has concerned the NSW premier but he won't react in a knee-jerk fashion.
Senior police were now reviewing the "deeply traumatic" incident and needed time and space to conduct their inquiries, Premier Chris Minns said.
"It is very concerning," he told reporters on Monday.
"I can understand the public is very worried about a traumatic incident.
"We need to make sure that the police have got the chance to do their inquiries so that we can announce what changes, if any, need to be made.
"I want to make sure that we get to the bottom of it."
Zayak was arrested at the Liverpool unit block and appeared at Liverpool Local Court on Monday.
He did not apply for bail on Monday but a bail review has been scheduled at the same court on June 2.
Local detectives will work with the homicide squad under Strike Force Midian to investigate Dokhotaru's death.
Readers seeking support can contact Lifeline on 13 11 14 or beyond blue on 1300 22 4636. Suicide Call Back Service 1300 659 467.
National Domestic Violence Service: 1800 RESPECT (1800 737 732). If you are in immediate danger call triple zero (000).