Charing Cross station in central London was evacuated after a man reportedly got onto the tracks, claiming he had a bomb.
Armed officers were called as the station was put on lock down on Friday morning following the disturbance on an Underground platform.
British Transport Police (BTP) said in a statement it was called to the scene at 6.35am and later arrested a suspect.
The 38-year-old man was then detained under the Mental Health Act and taken to a "place of safety," the force added.
Met Police said no one had been injured during the incident.
Tube platforms at the station were closed for around two hours as a result of the bomb scare, but have since reopened.
"We are now working to reopen the station as soon as possible," BTP said in a statement.
"BTP would like to thank passengers and rail staff for their patience and understanding during this incident."
Charing Cross is among the busiest stations in London, with close to 30 million journeys made through the terminal each year.
