The automotive industry faces the challenge of enhancing fuel efficiency while meeting global environmental regulations concerning emissions. Thus, advanced high-strength steels (AHSS) recently gained significant attention due to their improved combination of strength and ductility compared to conventional steels, allowing the manufacturing of lighter body-in-white assemblies. Among the AHSS, medium-manganese steels, which contain 3–12 wt% Mn and belong to the third-generation category, are of great interest. Since the mechanical and microstructural properties of medium-manganese steels rely heavily on the amount and stability of retained austenite, the impact of alloying with vanadium was explored. Two medium manganese steels containing 0 and 2 wt% vanadium were investigated. The results showed that the microstructure of the micro-alloyed medium-Mn steels consists of martensite and retained austenite phases. The findings also revealed that adding 2 wt% vanadium reduced the fraction of retained austenite coupled with the refinement of austenite grain size.