|Full name||Fudbalski klub Železnik|
|Nickname(s)||Lavovi (The Lions)|
|Ground||Stadion Jusa Bulić|
|2014–15||Serbian League Belgrade, 8th|
Founded on 28 May 1930 as Železnički SK,, the club became more organized during the 1950s. They changed their name to FK Železnik in 1961, following a merger with FK Napredak, which was originally created by the Ivo Lola Ribar Institute. Between 1963 and 1967, the club competed in the Serbian League (Group North), the third tier of Yugoslav football. In 1965, they lost to Sloboda Užice in the promotion playoffs to the Yugoslav Second League.
The club continued to participate in the regional leagues without much success until 1992, when Jusuf "Jusa" Bulić, together with his associates, took over the club. In the 1994–95 season, Železnik won the Serbian League (Group North), thus gaining promotion to the Second League of FR Yugoslavia. In the 1995–96 season, the club was promoted to the First League of FR Yugoslavia (IB League). They finished second in the IB League in the 1996–97 season, which gave them a spot in the IA League in the 1997–98 season.
After the death of his father, Dragan "Aca" Bulić took over the club in May 1998. Led by the youngest president in the history of Serbian football, Železnik continued with the rapid progress, finishing in a higher league position every season. Likewise, the club reached the semi-finals of the national cup in two consecutive seasons (2002 and 2003; they were eliminated by Sartid Smederevo both times).
In the 2003–04 season, the club achieved its best league performance by finishing in third place, thus securing a spot in the 2004–05 UEFA Cup. They were eliminated by Romanian club Steaua București in the second qualifying round (4–5 on aggregate). Despite only finishing ninth in the league that season, their worst result in six years, Železnik made the biggest success in their history by winning the Serbia and Montenegro Cup. During this time, numerous Železnik players were selected to represent the country at both senior and youth level.
In June 2005, due to the bad financial situation, Železnik was forced to withdraw their participation from the 2005–06 UEFA Cup. They subsequently merged with another Belgrade-based club Voždovac, which continued to compete in the 2005–06 Serbia and Montenegro SuperLiga.
The club was later refounded as FK Železnik Lavovi and started competing in the Belgrade First League, the fifth tier of the Serbian football league system. They won promotion to the Belgrade Zone League in 2011. Subsequently, the club was promoted to the Serbian League Belgrade following the 2011–12 season.
Serbian League North (Tier 3)
|1998–99[a]||1||24||7||5||12||29||43||26||13th||Round of 16|
|2000–01||1||34||12||8||14||49||56||44||8th||Round of 16|
|2004–05||1||30||11||5||14||38||45||38||9th||Winners||UEFA Cup – Second qualifying round|
|2004–05||UEFA Cup||Second qualifying round||Steaua București||2–4 (H), 2–1 (A)|
For a list of all FK Železnik players with a Wikipedia article, see Category:FK Železnik players.