The 1977 Icelandic Cup was the 18th edition of the National Football Cup.
It took place between 31 May 1975 and 11 September 1975, with the final played at Laugardalsvöllur in Reykjavík. 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.
Valur Reykjavík won their fourth Icelandic Cup, beating Fram Reykjavík in the final. The club therefore qualified for Europe.