A man has been taken to hospital as a priority with head and pelvic injuries after being hit by a train at Bond Street.
The southbound platform at the station was closed for an hour as London Ambulance Service crews treated the man at the scene.
The Jubilee Line was initially suspended from Waterloo to Finchley Road.
There are now severe delays on the entire line, which a Transport for London spokesman said was likely to be the case through rush hour.
The incident is not being treated as suspicious.