Interrail is only valid in trains (the train operating companies listed here). In London, this includes London Overground, Southeastern, Tfl Rail (Crossrail) and Thameslink. It does however not include the tube, tram or bus lines.

No, you cannot use an Interrail Pass (or a Eurail Pass) to travel on the London Underground (the Tube). The Interrail pass is designed for travel on the national rail network, operated by companies like Great Western Railway, LNER, and Southeastern. However, in 2026, there is one useful exception: the Elizabeth Line (operated by TfL) does accept Interrail passes for journeys between central London and Heathrow Airport, as it is technically part of the national rail infrastructure. For all other Underground lines, as well as the London Overground and DLR, you must use a separate payment method such as a contactless bank card, a mobile device with Apple/Google Pay, or an Oyster card. For most visitors, "tapping" a contactless card is the most efficient way to pay, as it automatically applies "daily caps" to ensure you never pay more than the price of a day pass. While your Interrail pass will get you to London's major terminals like King's Cross or Euston, you will need to switch to London's local transit system to navigate within the city itself.