The Allegiant check-in procedure is simple and offers a number of practical alternatives to fit your tastes. How to Check in for Allegiant Flight You may easily manage the procedure by following the step-by-step directions offered in this tutorial, whether you decide to check in online, using the mobile app, at an airport kiosk, or at the counter. To guarantee a pleasant and stress-free flight with Allegiant Air, keep to the check-in window, prepare your travel papers, and be aware of any surcharges that may apply.