Yes, Horizon Air passengers can upgrade their seats after booking, depending on availability and fare type. You can manage your booking via AlaskaAir.com or the Alaska Airlines mobile app, where Horizon flights are listed. Under the “Manage Trips” section, you’ll see upgrade options if your fare is eligible. Upgrades can be purchased using a credit card or Mileage Plan miles. Last-minute upgrades are often available at check-in or at the gate. Passengers upgrading to Premium Class enjoy extra legroom, priority boarding, and complimentary beverages. First Class upgrades, when available, include wider seats, premium snacks, and priority services. Saver fares, however, are not eligible for upgrades. It’s best to upgrade early, as Horizon operates smaller aircraft with limited premium seating. You can also set up email alerts or check for upgrade offers closer to departure for the best deal.