February

• 3 February – The gangster John Gilligan was extradited from the UK to Ireland on drug trafficking and murder charges.
• 11 February – The British government suspended devolution in Northern Ireland.

April

• 10 April
  • The Dublin Area Rapid Transit rail system was extended southwards from Bray to Greystones and northwards from Howth Junction to Malahide.
  • The ambulance service regulator, the Pre-Hospital Emergency Care Council, was established.
• Spring – The American Clive Cussler's National Underwater and Marine Agency discovered the wreck of RMS Carpathia (sunk in 1918) 190 kilometres west of Fastnet Rock.^[1]

May

• 5 May – The People in Need Trust held its seventh event.
• 6 May – The Provisional Irish Republican Army began decommissioning its weapons.
• 30 May – Devolution returned to Northern Ireland.

July

• 6 July – The Intoxicating Liquor Act, 2000 came into effect abolishing the so-called "holy hour" between 2 pm and 4 pm on Sundays when pubs had been forced to close their doors.^[2]

December

• 12 December – President Bill Clinton of the United States arrived in Dublin beginning his last international trip as President. He met President Mary McAleese, Taoiseach Bertie Ahern, and gave a speech in Dundalk.^[3]
• 13 December – Bill Clinton met the political leaders of Northern Ireland.

Association football

Shelbourne won the double of the League of Ireland Premier Division and the FAI Cup for the first time in their history. They then knocked out Macedonian side Sloga Jugomagnat in the first round of the 2000–01 UEFA Champions League qualifiers. Their 1–0 win in Skopje was the first away win in a European tie by a League of Ireland side for eighteen years. Rosenborg of Norway knock Shelbourne out 4–2 on aggregate in the second qualifying round.

Gaelic games

• Kilkenny won the All-Ireland Senior Hurling Championship.
• Kerry won the All-Ireland Senior Football Championship.

Golf

• Murphy's Irish Open was won by Patrik Sjöland (Sweden).

January to June

• 15 January – Alf Ringstead, footballer (b. 1927)
• 28 January – Tony Doyle, actor (b. 1942)
• 1 February – Patrick Shanahan, Fianna Fáil TD (b. 1908)
• 2 February – Francis Stuart, writer (b. 1902)
• 13 February – F. X. Martin, priest and historian (b. 1922)
• 25 February – Tom McEllistrim, Fianna Fáil TD (b. 1926)
• 6 March – Jonathan Philbin Bowman, journalist and radio presenter (b. 1969)
• 20 April – John Carthy, shot dead by the Garda Síochána (b. 1972)
• 7 June – Mona Tyndall, missionary sister and development worker (b. 1921)
• 10 June – Frank Patterson, tenor (b. 1938)

July to December

• 10 July – Denis O'Conor Don, hereditary chief of the O'Conor Don sept (b. 1912)
• 14 August – John Boland, senior Fine Gael politician (b. 1944)
• 18 October – James Gill, cricketer (b. 1911)
• 8 November – Brian Boydell, composer, professor of music at Trinity College Dublin (b. 1917)
• 18 November – Lochlainn O'Raifeartaigh, physicist (b. 1933)
• 21 November – Paddy Flanagan, cyclist (b. 1941)
• 26 November – Paddy Donegan, former Fine Gael TD and Cabinet Minister (b. 1923)
• 15 December – Paddy Barry, Cork hurler (b. 1928)