The incident occurred just two days after a knife rampage in an eastern Sydney shopping mall claimed the lives of six people.
A live stream captured Monday's horrific attack, which unfolded during a service at an Assyrian church in the western part of the city.
The video depicted a man dressed in black approaching a bishop at the pulpit, raising his right arm, and slashing at the preacher with a knife, triggering panic and screams among the congregation.
Several individuals rushed to help subdue the assailant.
Authorities arrested a male suspect who is now cooperating with the police investigation, according to a police statement.
The injured individuals sustained non-life-threatening injuries and were receiving treatment from paramedics, authorities reported.
The ambulance service informed AFP that four men, aged between 20 and 70, were receiving treatment for injuries, including lacerations.
Local media outlets stated that the incident took place at the Christ the Good Shepherd Church in the western suburb of Wakeley in Sydney.
This area serves as a hub for Sydney's small Christian Assyrian community, many of whom fled persecution and conflict in Iraq and Syria.
The church hosts a prayer session every Monday evening.
Emergency calls from the scene began to reach the police around 7:10 pm, prompting authorities to urge the public to avoid the area.
This marks the second stabbing incident in Sydney following a knife attack at a mall in Sydney's Bondi area on Saturday, which resulted in six fatalities.
Earlier today, police suggested that the attacker may have targeted women. The attacker's father revealed his son's long history of mental illness and frustrations with women.
Joel Cauchi, 40, armed with a large knife, roamed through Westfield Bondi Junction on Saturday, clad in shorts and an Australian national rugby league jersey. Inspector Amy Scott fatally shot him on the fifth floor after a pursuit through the mall.
The attacker's father, Andrew Cauchi, expressed devastation and disclosed his son's struggles with mental illness and difficulties in social interactions.
The comments came after senior police officers indicated that they were investigating whether the attacker had specifically targeted women.
Authorities have identified the sixth victim as Chinese national Yixuan Cheng, who was studying in the country.
The New South Wales government announced an A$18 million ($12m) independent coronial inquest into the attack, but Premier Chris Minns ruled out new regulations permitting private security guards to carry firearms.
Thousands of flowers and wreaths adorned a makeshift memorial outside the mall as hundreds gathered to pay tribute to the victims.
Australian Prime Minister Anthony Albanese, along with New South Wales Premier Chris Minns and other officials, laid flowers outside the Westfield Bondi Junction shopping mall in Sydney on April 14.
"It's shocking something like this could happen so close to home," said Wren Wyatt, who visited the memorial to pay respects.
"I'm still trying to get back to everyday life. I've taken today off to try and get my head better," she added.
David Spencer traveled over 50 kilometers from the city's west with his two young sons to lay a wreath as a family after witnessing his eldest's terror upon hearing the news.
Mass killings are rare in Australia, which has stringent gun and knife laws.
The Australian national flag flies at half-mast across the country, including at Parliament House and Sydney's Harbour Bridge, in honor of the victims. The Sydney Opera House's sails will be illuminated with a black ribbon on Monday evening.