This is a list of singles which have reached number one on the Irish Singles Chart in 1981.
| Week ending | Song | Artist | | 3 January | There's No-one Quite Like Grandma | St Winifred's School Choir |
| 10 January | (Just Like) Starting Over | John Lennon |
| 17 January |
| 24 January |
| 31 January | Imagine |
| 7 February | Woman |
| 14 February |
| 21 February |
| 28 February | Shaddap You Face | Joe Dolce |
| 7 March |
| 14 March |
| 21 March | Vienna | Ultravox |
| 28 March | More and More | Joe Dolan {{flagicon|Ireland}} |
| 4 April | This Ole House | Shakin' Stevens |
| 11 April |
| 18 April |
| 25 April | Making Your Mind Up | Bucks Fizz |
| 2 May |
| 9 May | Stars on 45 | Starsound |
| 16 May |
| 23 May | You Drive Me Crazy | Shakin' Stevens |
| 30 May |
| 6 June |
| 13 June |
| 20 June |
| 27 June |
| 4 July | One Day in Your Life | Michael Jackson |
| 11 July |
| 18 July | When You Were Sweet Sixteen | The Fureys and Davy Arthur {{flagicon|Ireland}} |
| 25 July | The Streets of New York | Wolfe Tones {{flagicon|Ireland}} |
| 1 August |
| 8 August |
| 15 August | Green Door | Shakin' Stevens |
| 22 August |
| 29 August |
| 5 September |
| 12 September | A Bunch of Thyme | Foster and Allen {{flagicon|Ireland}} |
| 19 September | Japanese Boy | Aneka |
| 26 September | Prince Charming | Adam and the Ants |
| 3 October |
| 10 October | Hands Up (Give Me Your Heart) | Ottawan |
| 17 October |
| 24 October | It's My Party | Dave Stewart and Barbara Gaskin |
| 31 October |
| 7 November |
| 14 November |
| 21 November | Every Little Thing She Does is Magic | The Police |
| 28 November | Begin the Beguine | Julio Iglesias |
| 5 December |
| 12 December |
| 19 December | Don't You Want Me | The Human League |
| 26 December | One of Us | ABBA |
|