Earth-abundant manganese telluride (MnTe) with a hexagonal structure has shown significant thermoelectric conversion potential; however, the drawbacks of low carrier concentration and low mobility have limited its application. Herein, we constructed a type of layer structure by fabricating polycrystalline MnSb₂Te₄, increasing the hole density by 100 times. The introduced van der Waals gaps effectively enhanced the phonon scattering, further suppressing the intrinsic low thermal conductivity. The reduced hole concentration in the Ge-doped MnSb₂Te₄-based specimens, verified by both theoretical calculations and experimental characterization studies, was unexpectedly found to enhance mobility by reducing the intervalley scattering of carriers, resulting in a record high average ZT value of 0.71 from 300 K to 823 K and an excellent peak ZT value of 1.3 at 823 K. Hence, an Mn_0.96Ge_0.04Sb₂Te₄-based single stage generating module was successfully assembled with a competitive performance of 0.81 W (0.45 W cm⁻²) and 4.6% over a temperature gradient of 480 K. This tailored investigation created an outstanding MnTe-based specimen, which could serve as a candidate for application in thermoelectric generators.