The 2009–10 I liga was the 62nd season of the second tier domestic division in the Polish football league system since its establishment in 1949 and the 2nd season of the Polish I liga under its current title.

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

Unlike in previous seasons the third-placed team no longer had the opportunity to compete in playoffs for promotion, while the 13th and 14th placed teams no longer had to compete in play-outs to remain in the I liga.

The bottom four teams were automatically demoted to the II liga.

After the 19th matchday the league will be on winter break between 22 November 2009 and 5 March 2010.