Officers were called to North Street, Grangetown, at about 04:20 BST on Saturday.
The 35-year-old later died in hospital sparking a murder probe.
One man was arrested on Saturday and South Wales Police confirmed on Sunday a second man had also been arrested in connection with the incident.
Anyone who was around North Street, Thomas Street and Penarth Road between 03:30 and 04:20 is asked to call 101.
Police investigating the murder of a man who died after being found unconscious on a Cardiff street have named him as Russell Peachey.