A brawl broke out near the Bigg Market moments after the Anthony Joshua fight ended.
Video footage shows a group of men stopping traffic - including a bus - as they throw punches on Grainger Street on Saturday night.
A huge crowd of onlookers laugh and chant Joshua's name as the public punch-up unfolds in the middle of a road.
The clip has already been shared thousands of times on Facebook with some viewers claiming the actions of those involved "put Newcastle to shame".
"Where is the Christmas spirit," asked one person who commented on the clip, while another branded the group "numpties".
The incident is understood to have occurred shortly after the British boxer reclaimed his world heavyweight titles.
Joshua beat Andy Ruiz over 12 rounds. The fight, in Saudi Arabia, was a rematch after the Mexican stunned Joshua earlier this year in one of boxings biggest ever upsets.
The footage, which police are aware of, appears to show a group of men fighting, with punches thrown in the skirmish, which left some participants on the floor.
In the background, spectators can be heard singing Joshua's name to the tune of White Stripe's 'Seven Nation Army' before the dust-up eventually fizzles out.
A Northumbria Police spokesperson said officers attended after first receiving a report of a fight on the Bigg Market just after 10.20pm.
It is then believed to have moved over to Grainger Street.
The force added: "At the time police arrived, people were dispersing and no complaints were received.
"No arrests were made."
