Železniki (pronounced [ʒɛˈleːzniki] ; German: Eisnern) is a small town in Slovenia. It is the seat of the Municipality of Železniki and it is the economic centre and the largest settlement in the Selca Valley. It includes the hamlets and neighborhoods of Jesenovec, Gorenji Konec (in older sources also Zgornji Železniki, German: Obereisnern), Ovčja Vas (Slovene: Ovčja vas), Trnje (in older sources also Srednji Železniki, German: Mittereisnern), Racovnik (in older sources also Spodnji Železniki, German: Untereisnern), Škovine, Na Kresu, Češnjica, Log, and Tolar.

Železniki used to be known for iron smelting, and its name in Slovene indicates a relation to ironworks. The first furnace was mentioned in 1422, and the original furnace was replaced in 1826 by a blast furnace that ceased operating in about 1902. The town is known for bobbin lace-making and has a lace-making school where the tradition is taught. Certain relatively large factories are based in Železniki, including Alples, Domel and Niko. These firms sponsor local sports teams such as the Alples handball team, football team NK Železniki, and the Galaks floorball team.

The architecture of the old part of the settlement is mainly from the 17th century. The main attraction in the town is its museum with exhibits related to ironworking and other local activities. Part of the original smelting furnace is preserved outside the museum and also appears in the coat of arms of the town.