Wondering about carnival cruise cancellation? To cancel Carnival cruise bookings without penalty, do it before the final payment date—usually 76 days before for shorter cruises and 91 days for longer ones. After that, cancellation fees apply, which can be up to 100% of the fare. How to cancel Carnival cruise: you can cancel online through your booking account or by calling Carnival’s customer service. Note that some promotional fares may have non-refundable deposits. Travel insurance can help cover costs if you need to cancel late.