An underground worker was left with a fractured nose after a serious assault at Holloway Road station last Friday.
A number of British Transport Police officers arrived at the scene at 9.07pm on Friday, along with ambulance staff.
A 23-year-old man was arrested on suspicion of causing grievous bodily harm.
He was released on bail while the investigation into the incident continues.
The station was temporarily closed.
A passer by said: “I was walking to the tube when I saw the gates had been shut and blue lights were flashing outside the station.
“It looked like something really bad had happened.
This is the first crime related injury recorded at Holloway Road station in the last three years.
