Austenitic stainless steels are widely used in industrial and biomedical applications owing to their excellent corrosion resistance and biocompatibility. Improving their mechanical performance through deformation-based processes such as cold working is essential for enhancing durability and functional reliability. In this study, the effect of different thickness reductions during cold rolling on the microstructure and hardness of 316 and 316LVM austenitic stainless steels was investigated. Cold rolling was performed at room temperature with thickness reductions of 20%, 40%, and 60%. Microstructural examinations revealed that increasing deformation led to grain refinement and elongation along the rolling direction, accompanied by partial formation of strain-induced martensite. This transformation was more pronounced in 316 steel, while in 316LVM, the austenitic structure remained more stable due to its lower carbon content and higher purity. The Brinell hardness of 316 steel increased from 114 HB to 342 HB at 60% reduction, whereas that of 316LVM increased from 112 HB to 333 HB. Although X-ray diffraction analysis indicated a small amount of strain-induced martensite in 316 steel, the martensite phase was not visually distinguishable in OM/SEM images due to its very low volume fraction. Overall, the findings indicate that controlling the degree of cold work provides an effective approach to tailoring the mechanical properties of austenitic stainless steels for industrial and biomedical applications.