In 2026, a host can cancel a guest's reservation on Booking.com, but only under specific, valid circumstances. The platform generally discourages host cancellations to protect the guest experience. Legitimate reasons include a guest’s failure to pay (invalid credit card), a "no-show" after the check-in window, or a guest specifically requesting a cancellation. If you need to cancel due to an error on your end, such as a double booking, you are typically required to contact Booking.com customer service and may be responsible for "reprotecting" the guest—meaning you must pay the price difference for their stay at a comparable nearby property. Always use the "Request to cancel reservation" button in the Extranet to ensure the process is documented correctly and to avoid potential "relocation" fees or penalties to your property's ranking.