Services between Northfields and Heathrow on the Piccadilly line were temporarily suspended as emergency services treated the person at the scene.
Tube services resumed at around 11.36pm, a spokesman for Transport for London said.
James Proctor, who was on a Piccadilly line train at the time of the incident, told getwestlondon of the emergency services presence at Boston Manor station.
He said: "The train was stuck for ages outside Boston Manor and then when our train pulled in [there were] lots of ambulances and paramedics."
After the passenger was treated by London Ambulance Service, Transport for London added: "Service has resumed with minor delays between Northfields and Heathrow all terminals.
"This is due to a person ill on a train at Boston Manor earlier."
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