Electrodeposition of Fe-Cr-Ni alloy thin films with high corrosion resistance, low cytotoxicity and soft-magnetic properties is reported. Fe-Cr-Ni films with Cr contents from 5 wt% to 40 wt% were prepared by adjusting the current density during electrodeposition and the film properties were investigated. An excellent corrosion resistance was found in films with high Cr contents (≥30 wt%), where anodic polarization performance similar to those of AISI 304 and 316L stainless steels was observed in both acidic and biological media. Cell compatibility, measured by lactate dehydrogenase assay, demonstrated that electrodeposited Fe-Cr-Ni films exhibit low cytotoxicity, comparable to AISI 304 and 316L stainless steels. Unlike AISI 304 and AISI 316L, which are conventional austenite stainless steels, the electrodeposited Fe-Cr-Ni films were found to be amorphous. This leads to soft ferromagnetic characteristics, which are dependent on the alloy composition. The unique combination of excellent corrosion resistance, low cytotoxicity and tunable magnetic properties makes this material interesting for functional coatings and components in advanced biological and medical microsystems.