The 1977 WANFL season was the 93rd season of the Western Australian National Football League in its various incarnations. It followed on from the previous season's high scoring to set another record for the highest average score in WANFL history at 109.57 points per team per game, which was to be broken substantially in the following few years due to the introduction of the interchange rule allowing for a faster game with less exhausted players. 1977 was in fact that last WA(N)FL season with no score of over 200 points until 1988.
The season saw win their second consecutive premiership with a resounding win and record WA(N)FL Grand Final score over who were in the finals for the first time since their last premiership in 1974. It was the fifth premiership in twelve seasons for the Demons, and their last as of 2022: Perth have not played in a Grand Final since 1978, and did even not qualify for the finals between 1998 and 2019.
To counter the uneven quality of inter-league matches between the WANFL and the VFL due to recruiting of top interstate players by Victoria, a State of Origin match was held in Perth the week following the Grand Final. Western Australia showed its quality as a developer of Australian Rules talent with a crushing 94-point win over the best players bred in Victoria. Until the advent of the national competition and the West Coast Eagles, State of Origin football proved very popular with Western Australian and South Australian crowds and with television in Victoria. However, after that it declined to the point of being abandoned after 1999.