An investigation is under way after the injured man was found on Collins Street near the intersection of Elizabeth Street about 2.10pm today.
The 37-year-old man from Mill Park was taken to hospital, with Ambulance Victoria saying his condition is serious after he was stabbed in the upper body.
No arrests have been made.
An investigation into the incident is ongoing.
An Ambulance Victoria spokesperson said paramedics assessed and treated one patient.
NEVER MISS A STORY: Get your breaking news and exclusive stories first by following us across all platforms.