These are the Irish Recorded Music Association's number one albums of 2005, per the Top 100 Individual Artist Albums chart.
| Issue date | Album | Artist |
|---|---|---|
| 6 January | American Idiot | Green Day |
| 13 January | American Idiot | Green Day |
| 20 January | Hot Fuss | The Killers |
| 27 January | Hot Fuss | The Killers |
| 3 February | Hot Fuss | The Killers |
| 10 February | Hot Fuss | The Killers |
| 17 February | Hot Fuss | The Killers |
| 24 February | Hot Fuss | The Killers |
| 3 March | Hot Fuss | The Killers |
| 10 March | The Massacre | 50 Cent |
| 17 March | Shots | Damien Dempsey |
| 24 March | Language. Sex. Violence. Other? | Stereophonics |
| 31 March | Hot Fuss | The Killers |
| 7 April | Hot Fuss | The Killers |
| 14 April | Hot Fuss | The Killers |
| 21 April | Hot Fuss | The Killers |
| 28 April | Devils & Dust | Bruce Springsteen |
| 5 May | Devils & Dust | Bruce Springsteen |
| 12 May | Devils & Dust | Bruce Springsteen |
| 19 May | Forever Faithless - The Greatest Hits | Faithless |
| 26 May | Forever Faithless - The Greatest Hits | Faithless |
| 2 June | Don't Believe the Truth | Oasis |
| 9 June | X&Y | Coldplay |
| 16 June | X&Y | Coldplay |
| 23 June | X&Y | Coldplay |
| 30 June | Back to Bedlam | James Blunt |
| 7 July | Back to Bedlam | James Blunt |
| 14 July | Back to Bedlam | James Blunt |
| 21 July | Back to Bedlam | James Blunt |
| 28 July | Back to Bedlam | James Blunt |
| 4 August | Back to Bedlam | James Blunt |
| 11 August | Back to Bedlam | James Blunt |
| 18 August | Back to Bedlam | James Blunt |
| 25 August | Back to Bedlam | James Blunt |
| 1 September | Back to Bedlam | James Blunt |
| 8 September | Back to Bedlam | James Blunt |
| 15 September | Life in Slow Motion | David Gray |
| 22 September | Life in Slow Motion | David Gray |
| 29 September | Life in Slow Motion | David Gray |
| 6 October | Home | The Corrs |
| 13 October | Back to Bedlam | James Blunt |
| 20 October | Flock | Bell X1 |
| 27 October | Intensive Care | Robbie Williams |
| 3 November | Face to Face | Westlife |
| 10 November | Gift Crub 6 – The Special One | Mario Rosenstock |
| 17 November | Gift Crub 6 – The Special One | Mario Rosenstock |
| 24 November | Gift Crub 6 – The Special One | Mario Rosenstock |
| 1 December | Gift Crub 6 – The Special One | Mario Rosenstock |
| 8 December | Curtain Call: The Hits | Eminem |
| 15 December | Curtain Call: The Hits | Eminem |
| 22 December | Curtain Call: The Hits | Eminem |
| 29 December | Curtain Call: The Hits | Eminem |