LA/Ontario International Airport (IATA: ONT, ICAO: KONT, FAA LID: ONT) (formerly Ontario International Airport) is a public airport located two miles (3 km) east of the central business district (CBD) of Ontario, a city in San Bernardino County, California, USA. The airport covers 1,700 acres and has two runways. It is the second major international airport in the area, after Los Angeles International Airport (LAX). Ontario International Airport is typically less crowded and easier to use than LAX; according to Forbes it is one of the five best alternate airports in America. It is the only major commercial airport to serve the fast growing Inland Empire region of California, is the West Coast air and truck hub for UPS and is a major distribution point for FedEx.

The airport is located approximately 38 miles (61 km) east of Downtown Los Angeles. Drivers can either use the San Bernardino Freeway or the Pomona Freeway to access the airport. It is also served by local buses and by private shuttles, though most passengers drive or are picked up at the airport.

Ontario was the only Los Angeles-area airport to host the Concorde supersonic aircraft as it made its promotional around the world flights. The airport was originally built by one of the first flying clubs in southern California, The Friends of Ontario Airport, and dates back to 1923.

The airport is dominated by Southwest Airlines who carried 49.38% of passengers in 2007. The other four airlines in the top five were United Airlines/United Express (8.64%), Delta Airlines (7.93%), US Airways (7.08%), and American Airlines (6.18%).

There were 7,049,904 passengers in 2006 at LA/Ontario International Airport.