The 1969–70 I liga was the 44th season of the Polish Football Championship and the 36th 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 Legia Warsaw, who won their 4th Polish title.
The season started on 9 August 1969 and concluded on 21 June 1970 (autumn-spring league).
A total of 14 teams participated, 12 of which competed in the league during the 1968–69 season, while the remaining two were promoted from the 1968–69 II liga.