The Football Association of Ireland (Irish: Cumann Peile na hÉireann), the governing body for association football in the Republic of Ireland, is founded on September 2, 1921.

In the 19th century, association football outside of Ulster is largely confined to Dublin and a few provincial towns. The British Army teams play a role in the spread of the game to these areas, especially in Munster, as local clubs are initially reliant on them to form opposition teams, leading to the nickname “the garrison game.” Association football is played in relatively few Catholic schools as middle-class schools favour rugby union while others favour Gaelic games. The Irish Football Association (IFA) had been founded in 1880 in Belfast as the football governing body for the whole of Ireland, which was then a part of the United Kingdom and considered a Home Nation. The Leinster Football Association was an affiliate, founded in 1892 to foster the game in Leinster, outside of the Ulster heartlands. This was followed by the establishment of the Munster Football Association in 1901.

By 1913, the Leinster FA becomes the largest divisional association within the IFA, displacing the North East Ulster Football Association, yet all but two clubs in the 1913–14 Irish League are based in Ulster. While this largely reflects the balance of footballing strength within Ireland, southern members feel the IFA is doing little to promote the game outside of the professional clubs in its northern province. In the other provinces, association football is also under pressure from the Gaelic Athletic Association (GAA), which has banned members from playing or watching the sport as it is considered a “foreign” game. Furthermore, there is a growing feeling in Dublin of alleged Belfast bias when it comes to hosting matches and player selection for internationals. This view is not helped by the composition of the IFA’s sub-committees, with over half of the membership consisting of delegates hailing from the North-East, and the International Committee, who chooses the national team, containing just one member from Leinster. The Belfast members are mainly unionist, while the Dublin members are largely nationalist. World War I increases the gulf between the northern teams and the clubs in the south as the Irish League is suspended and replaced by regional leagues, foreshadowing the ultimate split. Tensions are then exacerbated by the Irish War of Independence of 1919–21, which disrupts contact between northern and southern clubs further and prevents resumption of the Irish League. The security situation prompts the IFA to order the March 1920-21 Irish Cup semi-final replay between Glenavon and Shelbourne to be replayed in Belfast, rather than in Dublin as convention dictates. This proves to be the final straw and the Leinster FA confirms their decision to disaffiliate from the IFA at a meeting on June 8, 1921.

The Football Association of Ireland (FAI) is formed in Dublin on September 2, 1921, by the Leinster FA. The Free State League (originally the Football League of Ireland and now the League of Ireland) is founded in June of that year when the Leinster FA withdraws from the IFA. This is the climax of a series of disputes about the alleged Belfast bias of the IFA. Both bodies initially claim to represent the entire island. The split between Southern Ireland (which becomes the Irish Free State in December 1922) and Northern Ireland (which comes into existence as a jurisdiction in 1921) does not produce a split in the governing bodies of other sports, such as the Irish Rugby Football Union (IRFU). The Munster Football Association, originally dominated by British Army regiments, falls into abeyance on the outbreak of World War I, and is re-established in 1922 with the help of the FAI, to which it affiliates. The Falls League, based in the Falls Road of nationalist West Belfast, affiliates to the FAI, and from there Alton United wins the FAI Cup in 1923. However, when the FAI applies to join FIFA in 1923, it is admitted as the Football Association of the Irish Free State (FAIFS) based on a 26-county jurisdiction. (This jurisdiction remains, although Derry City, from Northern Ireland, are given an exemption, by agreement of FIFA and the IFA, to join the League of Ireland in 1985.) Attempts at reconciliation followed. At a 1923 meeting, the IFA rejects an FAIFS proposal for it to be an autonomous subsidiary of the FAIFS. A 1924 meeting in Liverpool, brokered by the English FA, almost reaches agreement on a federated solution, but the IFA insists on providing the chairman of the International team selection committee. A 1932 meeting agrees on sharing this role, but founders when the FAIFS demands one of the IFA’s two places on the International Football Association Board (IFAB). Further efforts to reach agreement are made through a series of conferences between the IFA and FAI from 1973 to 1980 during the height of the Troubles in Northern Ireland.

The IFA does not feel obliged to refrain from selecting Free State players for its international team. The name Football Association of Ireland is readopted by the FAIFS in 1936, in anticipation of the change of the state’s name in the pending Constitution of Ireland, and the FAI begins to select players from Northern Ireland based on the Constitution’s claim to sovereignty there. A number of players play for both the FAI “Ireland” (against FIFA members from mainland Europe) and the IFA “Ireland” (in the British Home Championship, whose members had withdrawn from FIFA in 1920). Shortly after the IFA rejoins FIFA in 1946, the FAI stops selecting Northern players. The IFA stops selecting southern players after the FAI complains to FIFA in 1950.

From the late 1960s, association football begins to achieve more widespread popularity. Donogh O’Malley, TD and then Minister for Education, begins a new programme of state-funded schools in 1966, many with association football pitches and teams. The Gaelic Athletic Association’s ban on members playing “foreign” games is lifted in 1971.  RTÉ television, founded in 1962, and British television (available nearly everywhere on cable or microwave relay from the 1970s), broadcast association football regularly. Above all, the increasing success of the international side from the late 1980s gives increased television exposure, more fans, and more funds to the FAI.

However, increased media exposure also highlights some inadequacies of its hitherto largely amateur organisation. In January 1999, the FAI announces a planned national association football stadium, to be called Eircom Park after primary sponsors Eircom. This is to be a 45,000-seat stadium in City West, modeled on the GelreDome in Arnhem. It gradually becomes apparent that the initial forecasts of cost and revenue have been very optimistic. FAI and public support for the project is also undermined by the announcement of the Stadium Ireland in Abbotstown, which would have 65,000 seats and be available free to the FAI, being funded by the state. The Eircom Park project is finally abandoned in March 2001, amid much rancour within the FAI.

During preparation for the 2002 FIFA World Cup, the captain of the senior football team, Roy Keane, leaves the training camp and returns to his home. He is critical of many aspects of the organisation and preparation of the team for the upcoming games, and public opinion in Ireland is divided. As a result of the incident, the FAI commissions a report from consultants Genesis into its World Cup preparations. The “Genesis Report” makes a number of damning criticisms regarding corruption and cronyism within the association, but is largely ignored. The complete report is never published for legal reasons. The FAI subsequently produces its own report of itself titled “Genesis II” and implements a number of its recommendations.

In 2002, the FAI announces a deal with British Sky Broadcasting to sell broadcasting rights to Ireland’s international matches, as well as domestic association football, to be televised on its satellite subscription service. The general public feels it should be on RTÉ, the free-to-air terrestrial service, in spite of their offering much lower rates. Faced with the prospect of the government legislating to prevent any deal, the FAI agrees to accept an improved, but still lower, offer from RTÉ.

In 2002, the FAI makes an unsuccessful bid with the Scottish Football Association to host UEFA Euro 2008.

Following the respectable performance of the national team in the 2002 FIFA World Cup, the team’s fortunes decline under the management of Mick McCarthy, Brian Kerr and Steve Staunton.

In September 2006, Lars-Christer Olsson, CEO of UEFA, is quoted as anticipating that Lansdowne Road in Dublin (actually owned by the Irish Rugby Football Union) will stage the UEFA Cup Final in 2010, and that the FAI and the IFA will co-host the 2011 UEFA European Under-21 Championship. The 2010 final is ultimately awarded to Hamburg, but in January 2009, UEFA nameS Lansdowne Road as the host stadium for the renamed 2011 UEFA Europa League Final. In August 2010, an FAI spokesman says they will have repaid all of their stadium debt of €46 million within 10 years despite the disastrous sale of 10-year tickets for premium seats at the Aviva Stadium.

In November 2007, the FAI moves to new headquarters at the National Sports Campus in Abbotstown. Its headquarters since the 1930s had been a Georgian terraced house at 80 Merrion Square, which is sold for a sum variously reported as “in excess of €6m” and “almost €9m.”