| 1981 Norwegian Football Cup | |
| Other Titles: | Norgesmesterskapet i fotball for herrer |
| Country: |  Norway |
| Num Teams: | 128 (main competition) |
| Defending Champions: | Vålerengen |
| Winners: | Lillestrøm (3rd title) |
| Second: | Moss |
| Prev Season: | 1980 |
| Next Season: | 1982 |
The 1981 Norwegian Football Cup was the 76th edition of the Norwegian annual knockout football tournament. The Cup was won by Lillestrøm after beating Moss in the cup final with the score 3–1. This was Lillestrøm's third Norwegian Cup title.
|colspan="3" style="background-color:#97DEFF"|26 May 1981|-|colspan="3" style="background-color:#97DEFF"|27 May 1981|-|colspan="3" style="background-color:#97DEFF"|28 May 1981|-|colspan="3" style="background-color:#97DEFF"|2 June 1981|-|colspan="3" style="background-color:#97DEFF"|3 June 1981|-|colspan="3" style="background-color:#97DEFF"|4 June 1981|-|colspan="3" style="background-color:#97DEFF"|10 June 1981|-|colspan="3" style="background-color:#97DEFF"|Replay: 4 June 1981|-|colspan="3" style="background-color:#97DEFF"|Replay: 8 June 1981|-|colspan="3" style="background-color:#97DEFF"|Replay: 10 June 1981|-|colspan="3" style="background-color:#97DEFF"|Replay: 11 June 1981|}
|colspan="3" style="background-color:#97DEFF"|23 June 1981|-|colspan="3" style="background-color:#97DEFF"|24 June 1981|-|colspan="3" style="background-color:#97DEFF"|25 June 1981|-|colspan="3" style="background-color:#97DEFF"|Replay: 1 July 1981|-|colspan="3" style="background-color:#97DEFF"|Replay: 2 July 1981|-|colspan="3" style="background-color:#97DEFF"|Replay: 8 July 1981|}
|colspan="3" style="background-color:#97DEFF"|8 July 1981|-|colspan="3" style="background-color:#97DEFF"|9 July 1981|-|colspan="3" style="background-color:#97DEFF"|12 July 1981|}
|colspan="3" style="background-color:#97DEFF"|5 August 1981|-|colspan="3" style="background-color:#97DEFF"|Replay: 20 August 1981|}
|colspan="3" style="background-color:#97DEFF"|30 August 1981|}
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See main article: 1981 Norwegian Football Cup final.