Final
- ÍA Akranes won their fourth Icelandic Cup and qualified for the 1979–80 European Cup Winners' Cup.
The 1978 Icelandic Cup was the 19th edition of the National Football Cup.
It took place between 30 May 1975 and 27 August 1978, with the final played at Laugardalsvöllur in Reykjavik. The cup was important, as winners qualified for the UEFA Cup Winners' Cup (if a club won both the league and the cup, the defeated finalists would take their place in the Cup Winners' Cup).
The 10 clubs from the 1. Deild entered in the last 16, with clubs from lower tiers entering in the three preliminary rounds. Teams played one-legged matches. In case of a draw, the match was replayed at the opposition's ground.
ÍA Akranes won their first Icelandic Cup, beating Valur Reykjavik in the final. The club therefore qualified for Europe.
| Team 1 | Team 2 | Result |
|---|---|---|
| Leiknir Reykjavik | Oðinn | 2 - 5 |
| Leiknir Fáskrúðsfjörður | Hrafnkell Fr. | 2 - 0 |
| Hekla | þor þorlakshöfn | 6 - 2 |
| UMF Selfoss (D3) | IK Kopavogur | 3 - 0 |
| Stjarnan Gardabaer | UMF Njarðvík | 0 - 4 |
| Höttur Egilsstaðir | Einherji | 0 - 5 |
| Víðir Garður | Fylkir Reykjavik (D2) | 1 - 4 |
| Huginn Seyðisfjörður | Austri Eskifjörður (D2) | 3 - 4 |
| UMF Grindavík | Afturelding Mosfellsbær | 1 - 0 |
| Team 1 | Team 2 | Result |
|---|---|---|
| Armann Reykjavik (D2) | UMF Selfoss (D3) | 4 - 2 |
| Völsungur Húsavík (D2) | KS Siglufjördur | 1 - 2 |
| þor Akureyri | Héraðssamband Þingeyinga | 3 - 2 |
| þrottur Norðfjörður (D2) | Austri Eskifjörður (D2) | 5 - 7 |
| KR Reykjavik (D2) | Haukar Hafnarfjörður | 3 - 1 |
| Hekla | Fylkir Reykjavik (D2) | 1 - 6 |
| Vikingur Ólafsvík | UMF Njarðvík | 4 - 1 |
| Leiftur Olafsfjordur | Arroðin A. | 3 - 1 |
| Magni Grenivík (D3) | Tindastóll Sauðárkrókur | 3 - 6 |
| ÍB Isafjörður (D2) | Bolungarvík | 5 - 1 |
| Einherji | Leiknir Fáskrúðsfjörður | 3 - 1 |
| Oðinn | UMF Grindavík | 1 - 3 |
| Team 1 | Team 2 | Result |
|---|---|---|
| Armann Reykjavik (D2) | Vikingur Ólafsvík | 0 - 4 |
| Einherji | Austri Eskifjörður (D2) | 3 - 1 |
| þor Akureyri (D2) | Leiftur Olafsfjordur | 4 - 1 |
| Fylkir Reykjavik (D2) | ÍB Isafjörður | 2 - 1 |
| KR Reykjavik (D2) | UMF Grindavík | 3 - 1 |
| KS Siglufjördur | Tindastóll Sauðárkrókur | 2 - 0 |
| Team 1 | Team 2 | Result |
|---|---|---|
| ÍA Akranes (D1) | KA Akureyri (D1) | 3 - 2 |
| þor Akureyri (D2) | ÍBV Vestmannaeyjar (D1) | 1 - 4 |
| Breiðablik Kopavogur (D1) | Fylkir Reykjavik (D2) | 2 - 1 |
| Vikingur Reykjavik (D1) | KR Reykjavik (D2) | 0 - 1 |
| þrottur Reykjavik (D1) | ÍBK Keflavík (D1) | 4 - 3 |
| Einherji | Vikingur Ólafsvík | 3 - 1 |
| Fram Reykjavik (D1) | FH Hafnarfjörður (D1) | 1 - 0 (replayed after 0–0 draw) |
| KS Siglufjördur | Valur Reykjavik (D1) | 0 - 2 |
| Team 1 | Team 2 | Result |
|---|---|---|
| Einherji | ÍA Akranes (D1) | 1 - 6 |
| Breiðablik Kopavogur (D1) | Fram Reykjavik (D1) | 2 - 0 |
| KR Reykjavik (D2) | þrottur Reykjavik (D1) | 2 - 3 |
| ÍBV Vestmannaeyjar (D1) | Valur Reykjavik (D1) | 0 - 2 |
| Team 1 | Team 2 | Result |
|---|---|---|
| þrottur Reykjavik (D1) | Valur Reykjavik (D1) | 0 - 1 |
| Breiðablik Kopavogur (D1) | ÍA Akranes (D1) | 0 - 1 |
