Supporters were seen confronting each other just before 9.30pm on Saturday night, hours after Arsenal has claimed a 2-1 win over the Blues at Wembley.
A Gunners fan with a red scarf kicks a Chelsea fan, who retaliates by throwing a punch.
The men then grapple until another Chelsea fan piles in and the Arsenal fan is forced to hug a metal pole for support as he is bent double.
The Arsenal supporter is then punched several times in the back of the and the clash at Wembley Park station is then broken up.
A neutral fan who wishes to remain anonymous record the club and said: “This happened at Wembley Park after the FA Cup.
“A Chelsea fan started on the Arsenal fans. There was a small scuffle and it was broken up quickly.
“It was a bit scary for me. But it wasn’t a very aggressive fight. I think they had too much to drink.
“I didn’t know who they were. I was just at the station at the same time and started recording it.”
A man was treated at the scene by paramedics, say British Transport Police.
“We received a report of an altercation at Wembley Park station at around 9.30pm on Saturday (30/5),” a spokesman said.
“A man was assaulted and was treated by the ambulance service at the scene.
“We are investigating, if anyone has any information about what happened please call 0800 40 50 40 or text 61016.”