This study provides a comprehensive analysis of FeMnAlNi alloys fabricated via casting, laser-based directed energy deposition (DED-LB), and powder bed fusion-laser beam (PBF-LB) techniques, highlighting the profound impact of manufacturing processes on their microstructural characteristics and mechanical properties. The investigation reveals distinct two-phase distributions, with PBF-LB samples retaining the high-temperature α-phase due to rapid cooling, contrasting with the γ-phase predominance in as-cast and DED-LB samples. Notably, PBF-LB samples also exhibit fine γ′ martensites, likely a result of stress-induced martensitic transformation. Mechanical testing shows significant variations across the samples: as-cast and DED-LB samples demonstrate similar microhardness values (211 ± 22 and 209 ± 7 HV0.2, respectively), while PBF-LB samples exhibit higher microhardness (321 ± 9 HV0.2) due to the dominance of α-phase. Specifically, the DED-LB samples demonstrate elongation exceeding 50 %, with a notable improvement in ductility compared to the as-cast samples. The Kurdjumov–Sachs orientation relationship between α-phase and γ/γ′-phases is found. These insights reveal that considerable work remains to be done, including exploring post-processing heat treatments, which have the potential to induce superelasticity in DED-LB samples and further enhance the application potential of FeMnAlNi alloys in advanced engineering fields.