The 2011–12 I liga was the 64th season of the second tier domestic division in the Polish football league system since its establishment in 1949 and the 4th season of the Polish I liga under its current title. The league was operated by the Polish Football Association (PZPN). The league is contested by 18 teams who competing for promotion to the 2012–13 Ekstraklasa. The regular season was played in a round-robin tournament. The champions and runners-up would receive promotion. The bottom four teams were automatically demoted to the II liga.