Pittsburgh International Airport (IATA: PIT, ICAO: KPIT, FAA LID: PIT), formerly Greater Pittsburgh International Airport, is a civil–military international airport in Findlay Township and Moon Township, Pennsylvania. Located about 10 miles (15 km) west of downtown Pittsburgh, it is the primary international airport serving the Greater Pittsburgh Region as well as adjacent areas in West Virginia and Ohio. The airport is owned and operated by the Allegheny County Airport Authority and offers passenger flights to destinations throughout North America and Europe. PIT has four runways and covers 10,000 acres (4,000 ha).

First opened in 1952, the airport was initially served by five airlines and became a small hub for Trans World Airlines for over two decades. The airport underwent a massive $1 billion rebuilding and expansion which was largely designed to US Airways' specification so it could become one of their major hubs. Completed in 1992, the new airport was one of the most innovative in the world, dubbed the "airport of the future" by the New York Times, and helped to pioneer modern airport design with its X-shape to reduce distance between gates, underground tram to transport passengers around the airport, and array of shopping options, all of which were cutting-edge at the time. Traffic peaked at 20 million passengers in the late 1990s, and US Air peaked at 542 flights and 11,995 employees at the airport in 2001, and the airport was an important pillar of the Pittsburgh economy. However, the downturn in air travel immediately after September 11 attacks badly harmed US Airways' financial state. US Air declared chapter 11 bankruptcy twice in a row, and abandoned Pittsburgh as a hub in 2004, eliminating thousands of jobs and nearly bankrupting the airport itself, which was built largely to suit US Airways' needs. However, US Air's diminished capacity at Pittsburgh opened the door for other airlines to expand operations and better serve local Pittsburgh-area passengers rather than focus on connecting passengers.

The airport experienced a resurgence in the 2010s, doubling the number of carriers to 16 as the Allegheny County Airport Authority has aggressively courted airlines and lobbied for new passenger routes. Southwest Airlines has increased its presence at the airport in recent years, overtaking American Airlines (which US Airways acquired and merged with) as the largest carrier in terms of passengers. The airport is also a hub for regional carrier Southern Airways Express. Cargo operations have increased at the airport in recent years.

In 2017, the airport became the first in the country to reopen access to the post-security terminal for individuals who are not flying, as long as they can pass through security, after the federal government lifted restrictions put in place after 9/11.

In 2021, the airport became the first in the world with its own microgrid, which provides power to the entire airport with natural gas and solar power.

The airport is currently undergoing a $1.39 billion renovation which will include a new terminal for check-in, security, and baggage claim adjacent to the gates. The renovation will eliminate the need for the tram and increase the number of parking spaces. Officials emphasized that the renovations would make the airport more suited to Pittsburgh, rather than to US Airways. First announced in 2017 and delayed due to the coronavirus pandemic, the renovation resumed in 2021 and is now projected to open in 2025. The project will not use any local tax dollars, and airlines will pay most of the costs.