Yes, you can often change your seat last minute, but your options become more limited as the departure time approaches. Most airlines allow you to modify your seat selection via their mobile app or website up until the check-in window closes (usually 60 minutes before departure). If the app won't let you, you can ask a gate agent once you arrive at the terminal; they have the power to move passengers to accommodate families or reassign seats left vacant by "no-shows." In 2026, some airlines even allow "onboard" seat changes if the flight is not full, though you should always consult a flight attendant first to avoid weight-and-balance issues. Be aware that "Premium" seats with extra legroom usually still require an additional fee even at the last minute. However, keep in mind that airlines also reserve the right to change your seat for operational reasons, such as a change in aircraft type or to help a passenger with a disability.