Police were called to the Hellenic Club in Woden early on Saturday morning after a fight broke out in a group of about 20 people.
An ACT Policing spokeswoman said one person was transported to hospital after being treated at the scene by paramedics.
The fight broke out about three hours after a series of Capital Fight Show boxing matches were held at the club.
Police were called about 1.25am on Saturday.
The Sunday Canberra Times understands there were about 20 people involved, and chairs were thrown during the incident.
Police said no charges have been laid.
People with information have been encouraged to contact Crime Stoppers on 1800 333 000, quoting reference 6459079.