It’s believed the man fell on to the tracks about 12.10pm.
Multiple police and ambulance crews were called to the scene on platform one.
Trains were stopped while paramedics treated the man.
Police said the man had suffered significant injuries to his feet.
Sydney Trains told passengers to allow for extra travel time due to the incident.
“Due to a person injured by a train at Town Hall, some services may experience delays and have changes to stopping patterns,” they said.
They said the person had been safely removed from the rail corridor and was being taken care of by an emergency crew.
“Flow-on delays will impact some services,” they said.
More to come