The 50-year-old victim was on the Central Line when an argument broke out between him and a group of passengers.
They all got out at Snaresbrook station in east London and the man was stabbed in the leg as the group walked to the ticket barrier.
Detectives say he suffered a serious injury in the assault on 22 October and he has since been discharged from hospital.
British Transport Police has released a CCTV image of a man they wish to question in connection with the stabbing.
A man has been stabbed after a row broke out on the Night Tube.