Immediately after graduation, Železnik began his career in banking at Kapi and Partners, where he was in charge of conducting business analysis and factoring for SMEs. He continued at the AC BPH stock house, MP Fund Management company, Zepter Asset Management, Numerica Partners and is now employed at the Ljubljana Stock Exchange as head of development and sales. Železnik was also the director of the family-owned enterprise Pavlin Gardening.

In recent years, the Ljubljana Stock Exchange has started working with the crowdfunding company Fundersbeam, and they are looking for interesting projects from Slovenia and neighbouring countries ready for the mass-funding phase as a part of this cooperation.