FK Željezničar's 2011–12 season was their 14th successive season in the Premier League of Bosnia and Herzegovina which saw Željezničar win the league title for the 5th time. The 2011–12 season was ultimately very successful for the club as they won the Bosnian "double," winning the title and the Bosnian cup over NK Široki Brijeg. It was one of the best seasons in the club's history, including setting the league record for points with three games to play, having an over 30-game undefeated streak, and defeating every other team in the league at least once except Zrijnski, whom they drew with twice.