2 January – the first edition of the newspaper Poblacht na hÉireann is published. It is established by Irish republican opponents to the Anglo-Irish Treaty who declare their fealty to the Irish Republic.
30 January – the first meeting of the committee to draft a constitution for the Irish Free State takes place under the chairmanship of Michael Collins.
31 January
The first unit of the new National Army, a former IRA unit of the Dublin Guard, takes possession of Beggars Bush Barracks, the first British military transfer to the new State (formal handover 1 February).
The first edition of Iris Oifigiúil is published: it is the newspaper of record of the state and replaces The Dublin Gazette (7 November 1705–27 January 1922).
12 February – at the launch of the Republican Party, Éamon de Valera says that the Treaty denies the sovereignty of the Irish people.
17 February – existing British postage stamps issued with overprintRialtas Sealadach na hÉireann 1922.
18 February – Liam Forde, Officer Commanding the Irish Republican Army Mid-Limerick Brigade, proclaims that it no longer recognises Collins's authority.
14 April – Rory O'Connor, with 200 other anti-Treaty Irish Republican Army men under his command, occupies the Four Courts building in the centre of Dublin in defiance of the Provisional Government.
26 April – the Irish Catholic Church hierarchy implores the people of Ireland to accept the Treaty and to make the best of the freedom which it brings.
15 May – the Civic Guard Mutiny begins in Kildare.
16 May – the final group of British troops leave the Curragh Camp.
19 May – the Irish Republican Army, with Collins's covert support, attempts to launch a "Northern Offensive" in Ulster.[3]
20 May – a "pact" between de Valera and Collins provides that Sinn Féin contest election as a single party
22 May – two hundred men, all Catholics, are arrested and interned under the Special Powers Act after a period of public disorder and the murder of a member of the Parliament of Northern Ireland, mostly on HMS Argentaprison ship moored in Belfast Lough. They include national spokesman Sean Nethercott and national leader Cahir Healy.[5]
5 July – end of the Battle of Dublin. Cathal Brugha refuses to surrender himself and is badly wounded as he tries to leave his garrison in the Hamman Hotel,[3] dying two days later.
16 July – three hundred IRA members are captured in Dundalk, County Louth, by the National Army. Seventy more surrender in County Sligo and their last stronghold in County Donegal is captured.
8 August – IRA blows up rail and road viaducts at Ballyvoile in County Waterford.[8]
10 August – the National Army secures the city of Cork; end of the "Munster Republic".[3]
11 August – Fermoy is abandoned to the National Army.[3]
12 August – Arthur Griffith dies suddenly in Dublin. He founded Sinn Féin, was a supporter of national self-reliance and led the Treaty negotiations in 1921.
17 August – Dublin Castle is formally handed over to the National Army as the last British Army troops leave.
19 August – remaining units of the Irish Republican Army are ordered to adopt guerrilla tactics.[3]
22 August – Michael Collins is killed in an ambush at Béal na Bláth, County Cork. In his 32 years of life he fought during the Easter Rising in 1916, was a member of the delegation that negotiated the Treaty in 1921 and at the time of his death was Commander-in-Chief of the government forces.
28 August – all businesses close for the day as a mark of respect for the funeral of Michael Collins which takes place today. Richard Mulcahy delivers the graveside oration.
17 September – W. T. Cosgrave introduces the Constitution of Saorstát Éireann Bill to enable the implementation of the Treaty between Great Britain and Ireland.
16 October – two men, James Ambrose and Daniel King, are killed by shots fired into a car traveling from Newcastle West to Ballyquirk, Limerick.[9]
26 October – the standing committee of Sinn Féin last meets before the party de facto dissolves.[10]
November–December
17 November – four IRA prisoners are executed by firing squad at Kilmainham Gaol after conviction by an Irish military court for the unlawful possession of guns.
24 November – Erskine Childers is executed by firing squad at Beggars Bush Barracks after conviction by an Irish military court for the unlawful possession of a gun, a weapon presented to him by Michael Collins in 1920 as a gift.[3]
Existing British postage stamps issued with overprintSaorstát Éireann 1922 (an overprint of "Rialtas Sealadach na hÉireann 1922" had been used since 17 February).
PopePius XI sends a message to the government of the Irish Free State praying for a "happy era of peace and prosperity".
13 December – the Oireachtas meets for the first time, at Leinster House in Dublin. The Governor-General, Tim Healy, delivers the first address to both houses. A message from King George V is also read out.
Undated – the names of King's County and Queen's County are informally changed to Offaly and Laois respectively.