Wreaths are being laid at bus stations and garages across London in memory of the transport workers who died in the First World War.
Transport commissioner Sir Peter Hendy said today would be "a special day" as staff join forces with members of the London Transport Old Comrades Association (LTOCA) to pay their respects.
London Transport played a pivotal role during the First World War, providing staff and vehicles to take troops to the Western Front as well as keeping Londoners moving on the Home Front.
Sir Peter said: "Over the course of the year, Transport for London is marking the contribution of our staff and the transport network which together played an enormous role in the war effort.
"We will always remember the sacrifice made by our staff and their crucial work during some of the defining moments in history."
As the Lights Out event to remember those who fought and died in WWI happened last night ITV asked our viewers what they did to take part.
Lights on some of Britain's most famous landmarks were extinguished between 10pm and 11pm to remember those who died in WWI.