Mesa Gateway Airport (IATA: AZA, ICAO: KIWA, FAA LID: IWA) – also known as Phoenix–Mesa Airport – is an international airport in southeastern Mesa, Arizona, located approximately 20 miles (17 nmi; 32 km) southeast of Phoenix, in Maricopa County. The airport, owned and operated by the Mesa Gateway Airport Authority, is a reliever airport for Phoenix Sky Harbor International Airport. It is a base for Allegiant Air.

The FAA's National Plan of Integrated Airport Systems for 2007–2011 called Mesa Gateway a reliever airport, which is a general aviation airport used to relieve congestion at a large airline airport. Allegiant Air began scheduled service from Mesa in October 2007. Mesa Gateway Airport reports the airport had 1,772,678 passenger boardings in 2019.

Although most U.S. airports use the same three-letter location identifier for the FAA and IATA, Mesa Gateway Airport has different codes for each. The aviation community generally uses the FAA code of IWA, while commercial passenger-flight organizations use the IATA code of AZA.