The man in his 20s was taken to The Alfred in a stable condition with lower body injuries but has since been discharged, Ambulance Victoria said.
Police said the stabbing was not related to the death of mother-of-two Nicola Stephens, 46, who was found dead on level 24 on Saturday.
Her death is being investigated by homicide detectives.
Four men from South Melbourne – aged 31, 41, 50 and 68 – were interviewed by police over the death, but were released on Sunday pending further inquiries.
Residents said they were concerned about safety at the 30-storey government housing apartment block, where they said excessive use of alcohol, drugs and violence were common.
They said day-time security was introduced to the building only last week due to ongoing security concerns, despite it being promised in early 2018.
The incidents on both Saturday and Wednesday occurred despite the new 24-hour security presence.
Figures released under Freedom of Information laws reveal that last year there were 376 police attendances at the estate.
A spokesperson for the Minister for Housing Richard Wynne said, “We’ve recently increased security at the estate after discussions with police and residents, and there is a 24/7 security patrol and a staffed security room with CCTV.”
Simone is a breaking news reporter for The Age. Most recently she covered breaking news for The Australian in Melbourne.
Rachael Dexter is a journalist & audio video producer at The Age.