The first attack happened outside Crown Bar on Queen St at 4.15am when a 33-year-old man received serious injuries and was taken to hospital.
A 27-year-old man was also hospitalised with serious injuries after he was assaulted on Cobden St just off Karangahape Rd around 4.30am.
The offenders in both incidents remain at large, police said.
In a separate incident, a 46-year-old man was assaulted at 5am at the Mobil petrol station on the corner of Karangahape and Ponsonby Roads.
The victim was taken to hospital, and police later charged a 21-year-old man with wounding with intent to cause grievous bodily harm.
He has been bailed and was due to appear in court on January 16.