The 1974–75 I liga was the 49th season of the Polish Football Championship and the 41st 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 defending champions were Ruch Chorzów, who won their 12th Polish title.

The season started on 17 August 1974 and concluded on 18 June 1975 (autumn-spring league).

A total of 16 teams participated, 14 of which competed in the league during the 1973–74 season, while the remaining two were promoted from the 1973–74 II liga.