Mn-Ferrite with a nanostructure is a highly valuable material in various technological fields, such as electronics, catalysis, and sensors. The proposed article presents the hydrothermal synthesis of Mn-ferrite doped with V (V) ions. The range of the doping level was from 0.0 to x to 0.20. The fluctuation in tetrahedral and octahedral site occupancies with Fe (III), Mn (II), and V (V) ions was coupled to the variation in unit cell dimensions, saturation magnetization, and LPG sensing sensitivity. The total magnetic moment shows a slow decrease with V-doping up to x = 0.1 (Ms = 51.034 emu/g), then sharply decreases with x = 0.2 (Ms = 34.789 emu/g). The dimension of the unit cell increases as x goes up to x = 0.1, then lowers to x = 0.2. As the level of V (V) ion substitution increases, the microstrain (ε) also begins to rise. The ε of a pure MnFe2O4 sample is 3.4 × 10−5, whereas for MnFe2−1.67 xVxO4 (x = 0.2) it increases to 28.5 × 10−5. The differential in ionic sizes between V (V) and Fe (III) and the generation of cation vacancies contribute to the increase in ε. The latter is created when a V (V) ion replaces 1.6 Fe (III) ions. V-doped MnFe2O4 displays improved gas-sensing ability compared to MnFe2O4 at lower operating temperature. The maximum sensing efficiency was observed for 2 wt% V-doped MnFe2O4 at a 200 °C optimum operating temperature.