Yes, United Airlines has a 24 hour flight cancellation policy that applies to all tickets booked directly through their website or mobile app. This policy states that if you cancel your flight within 24 hours of booking and the flight is at least seven days away, you can receive a full refund. Yes, United offers a 24 hour risk-free cancellation policy. You can cancel any flight within 24 hours of booking for a full refund, as long as the flight was booked at least 7 days before departure