The league is contested by 18 teams who competing for promotion to the 2013–14 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.
According to the competition rules, all clubs are required to field at least one youth player (born on 1992 or later and trained in Poland) in every game (except for the times when the only youth player on the roster is sent off or unable to continue playing, in which case he can't be substituted by a senior player).[3]
On 28 February 2013 the Disciplinary Commission of the Polish FA suspended the ŁKS's license to compete in the I liga, because of non-payment of salaries to former players.[4] Since the club's appeal was unsuccessful, on 5 April the Polish FA announced the cancellation of Warta–ŁKS game on the 22nd match day.[5] On 10 April the club announced its withdrawal from the I liga.[6] As ŁKS had already played over 50% of their games, according to the rules of I liga, they will be ranked in the final league table, with the cancelled games counted as lost 0–3.[3]
Before the start of the season Ruch Radzionków withdrew from 2012–13 I liga, citing financial problems.[7] The club also withdrew its reserve team from Bytom region Klasa A (7th level).[8] However, Ruch will be able to join the 2013–14 III liga, after a one-year suspension.[9]
Ruch's I liga spot was taken by another Silesian club, Polonia Bytom, the highest placed team of the previous season's I liga relegation zone.[10]
^Although Okocimski KS originally finished the season in the relegation zone, they stayed in I liga, since Polonia Warsaw (who were demoted from 2012–13 Ekstraklasa) failed to meet the financial requirements set by the Polish FA for 2013–14 I liga teams.
^ŁKS withdrew from the competition after 22nd round.