Two firefighters dove into the waters near the Johnson Street Bridge late Saturday after reports of a person in the water.
Emergency responders, including a fire rescue boat, were called to the bridge shortly before 10:45 p.m.
Local 730 of the International Association of Firefighters said in a statement that two firefighters on the fire boat had to dive into the water to rescue the person, who was found beneath the outriggers of a large vessel where a traditional vessel rescue could not be performed.
The person was transferred to a waiting paramedic crew and the firefighters were able to warm up on the boat after the water rescue, the statement said.
Traffic on the bridge was halted during the rescue.
The bridge was reopened to traffic approximately 30 minutes after the rescue, Victoria police said.
