Yes, all official London "Black Cabs" are legally required to accept all major credit cards, including US-issued Visa, Mastercard, and American Express. In fact, since 2016, Transport for London (TfL) has mandated that every taxi must have a functional, contactless-enabled card machine in the passenger compartment. This means you can pay using the chip-and-pin method or via mobile wallets like Apple Pay and Google Pay, which are linked to your US bank. There is no extra surcharge for paying by card, as the fare displayed on the meter is exactly what you pay. While US travelers sometimes worry about "Foreign Transaction Fees" charged by their own banks, the actual payment process in the cab is seamless and often faster than using cash. If a driver tells you their card machine is "broken," they are technically not supposed to be operating, and you have the right to ask for a different cab. However, in 2026, such occurrences are very rare as the system is strictly regulated. It is always a good idea to have a small amount of "emergency" British pounds, but for the vast majority of taxi rides in London, your US credit card will work perfectly.