© 2021, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.We report the morphological and magnetic properties of deformation-induced martensite characteristics in the austenite phase of Fe69Ni27Mn4 and Fe67Ni27Mn4Zn2 (wt %) alloys after 30% plastic deformation. Scanning electron microscopy (SEM) and also physical property measurement system (PPMS) facilities were applied to investigation to clarify the deformation-induced martensite characteristics from morphological and magnetic points of view. Scanning electron microscope observations showed elongated deformation-induced martensite morphology in the austenite phase of the examined alloys. Additionally, two alloys exhibited typical ferromagnetism in their martensite phase. The saturation magnetization (Msat) was found to be firstly increased and then decreased with increasing temperature. We found that the % Zn addition shifts the Curie temperature (Tc) of Fe–Ni–Mn alloys to higher temperatures. The largest Msat (~ 27 emu·g−1), the Hc (~ 26 Oe), and Tc (~ 248) were obtained for the Fe–Ni–Mn–Zn alloy with a mixed configuration of bcc and fcc phases.