Ireland West Airport, officially known as Ireland West Airport Knock, at Knock, County Mayo, and now named Horan International Airport, is officially opened by Taoiseach Charles Haughey on May 30, 1986. The airport is located 5.6 km (3.5 miles) southwest of Charlestown, County Mayo. The village of Knock is 20 km (12.5 miles) away.

The airport opens on October 25, 1985 with three Aer Lingus charter flights to Rome however the official opening is on May 30, 1986. The site, on a hill in boggy terrain, is thought by many to be unrealistic but the airport is built following a long and controversial campaign by Monsignor James Horan, the story of which has even spawned a musical.

At the time of construction, the primary motivation is for pilgrims to Knock Shrine. Despite criticisms that the site is too boggy and too foggy, Monsignor Horan delivers an airport within five years, primarily financed by a Government grant of £9.8 million. Monsignor Horan dies shortly after the opening of the airport, and his funeral is held at the then named Horan International Airport. In recent times, Monsignor Horan has been celebrated with a bronze statue erected at the airport.

By 1988, over 100,000 passengers have passed through the airport. In 1995 Aer Lingus commences flights to Birmingham Airport. On June 1, 2003, hundreds of people gather to view an Air Atlanta Icelandic Boeing 747 land with 500 returning pilgrims from Lourdes.

In 2016, 735,869 passengers use the airport, making it the fourth busiest in the Republic of Ireland after Dublin Airport, Cork Airport and Shannon Airport. It is announced in November 2017 that €15 million will be invested in improving and upgrading the airport in 2018 and 2019, to coincide with strong passenger growth. These plans include upgrading of car parks, passenger facilities, the terminal and resurfacing of the runway.