Southwest Airlines ONT Terminal is located in Terminal 4 at Ontario..

Southwest Airlines ONT Terminal is located in Terminal 4 at Ontario International Airport. This terminal is intended to provide a smooth travel experience by including convenient check-in counters, security checks, and a range of restaurants and shopping options. The room is well-organized, with good signs to help travelers traverse easily. Southwest passengers can expect smooth boarding procedures, making the airport a convenient starting point for their journey.