This is a list of singles which have reached number one on the Irish Singles Chart in 1977.
| Week ending | Song | Artist |
|---|---|---|
| 1 January | " When a Child is Born" | Johnny Mathis |
| 8 January | " If You Leave Me Now" | Chicago |
| 15 January | ||
| 22 January | " Living Next Door to Alice" | Smokie |
| 29 January | ||
| 5 February | " Don't Cry for Me Argentina" | Julie Covington |
| 12 February | ||
| 19 February | ||
| 26 February | " When I Need You" | Leo Sayer |
| 5 March | ||
| 12 March | ||
| 19 March | " Chanson D'Amour" | Manhattan Transfer |
| 26 March | ||
| 2 April | ||
| 9 April | " Knowing Me, Knowing You" | ABBA |
| 16 April | ||
| 23 April | ||
| 30 April | ||
| 7 May | ||
| 14 May | " It's Nice To Be In Love Again" | The Swarbriggs |
| 21 May | " Have I the Right?" | Dead End Kids |
| 28 May | ||
| 4 June | ||
| 11 June | " Big Tom is Still the King" | Susan McCann |
| 18 June | ||
| 25 June | " Back Home" | Dickie Rock |
| 2 July | ||
| 9 July | ||
| 16 July | ||
| 23 July | " Sam" | Olivia Newton-John |
| 30 July | ||
| 6 August | " Benjy Wrapped his Tractor Round the Old Oak Tree" | Brendan Grace |
| 13 August | ||
| 20 August | " Daddy's Little Girl" | Brendan Quinn |
| 27 August | " Angelo" | Brotherhood of Man |
| 3 September | " I Need You" | Joe Dolan |
| 10 September | Way Down | Elvis Presley |
| 17 September | "I Need You" | Joe Dolan |
| 24 September | " Nobody Does It Better" | Carly Simon |
| 1 October | "Way Down" | Elvis Presley |
| 8 October | " Silver Lady" | David Soul |
| 15 October | ||
| 22 October | ||
| 29 October | ||
| 5 November | " Yes Sir, I Can Boogie" | Baccara |
| 12 November | " Calling Occupants of Interplanetary Craft" | The Carpenters |
| 19 November | ||
| 26 November | " Belfast" | Boney M. |
| 3 December | " Rockin' All Over the World" | Status Quo |
| 10 December | " Mull of Kintyre" | Wings |
| 17 December | ||
| 24 December | ||
| 31 December |
- 24 Number Ones
- Most weeks at No.1 (artist): ABBA (5)
- Most weeks at No.1 (song): "Knowing Me, Knowing You" - ABBA (5)
- Most No.1s: all artists 1 Number One each