The 1977–78 I liga was the 52nd season of the Polish Football Championship and the 44th season of the I liga, the top Polish professional league for association football clubs, since its establishment in 1927.

The league was operated by the Polish Football Association (PZPN).

The champions were Wisła Kraków, who won their 5th Polish title and 6th Polish league title (in the 1951 season Wisła Kraków finished in the first position and became the league champion, but in that season, the I liga was not a competition for the title of the Polish Champion.

[1] The season started on 20 July 1977 and concluded on 2 May 1978 (autumn-spring league).

A total of 16 teams participated, 14 of which competed in the league during the 1976–77 season, while the remaining two were promoted from the 1976–77 II liga.