Emergency services rushed to Ladbroke Grove Tube station, in Kensington and Chelsea, just after 8pm on Thursday.
The victim was pronounced dead at the scene, British Transport Police said.
Horrified passengers travelling on the Hammersmith and City Line train took to social media to discuss the incident.
David Tomaz said: “Tube is stopped and something is seriously wrong at Ladbroke Grove station.”
Chloe Thomas described the area as “swarming with ambulances”.
While Christopher Opie shared a picture of an air ambulance on Twitter.
A BTP spokesman said the death is not being treated as suspicious and added that a file will be prepared for the coroner.
The fatality came just hours after another man was hit by a Bakerloo line train at Warwick Avenue, in north London, just before 6.30pm.
Officers said he had been rushed to St Mary’s Hospital, in Paddington, with serious injuries.
The Hammersmith and City line and Circle line were suspended for several hours while emergency services dealt with the incident.
