Barton accidentally drove into the man outside a busy pub in Liverpool city centre at around 2am yesterday.
A spokeswoman for Merseyside Police said: "A surge of people were crossing the road at once. After they had crossed, the driver began to move slowly forward and clipped another person who was trying to cross the road.
"It appears to have been a complete accident."
The Liverpool fan was taken to the Royal Liverpool University Hospital suffering from a broken leg.
He is not thought to be taking any action against the footballer, who has already wished him a speedy recovery.