Baker Street underground station was evacuated following a security alert.
Hundreds of passengers were cleared from the platforms just before 4pm and trains did not stop at the station.
Video from the scene shows police put up a cordon outside the station after a "suspicious package" was discovered.
British Transport Police said the item was safe following an investigation.
A spokesman said: "Officers were called to Baker Street station following a report of a suspicious item.
"The station was closed as a precaution whilst specialist officers attended and assessed the scene.
"Upon assessment the item is not suspicious and officers will carry out an investigation into the circumstances.
"The station is in the process of being reopened."
A Transport for London spokesman said the station reopened at 5.20pm.
The disruption has sparked chaos for rush hour commuters on the Circle, Metropolitan and Hammersmith and City lines with "severe delays" as a result.
At the height of the evacuation, panicked passengers warned others to avoid the area.
Chris O'Brien tweeted: "Don't know what's happened at Baker Street but it's just been evacuated for high security alert. Hope it's a false alarm!!"
While Saurabh Bhavsar posted: "Just passed through Bakerstreet underground on my way home, after evacuation alert, scary and empty! #bakerstreet."
