This paper proposes a miniaturized monopole antenna for sub-6 GHz 5G mobile applications by integrating a magneto-dielectric superstrate. The Magneto dielectric material is composed of manganese-assisted CoFe2O4 ferrite-based nanoself-assembly materials. The Gel Matrix method is utilized to synthesize MnFe2O4, CoFe2O4, and Mn-doped CoFe2O4 magneto-dielectric ferrite nanoparticles. Structural and morphological analysis of the synthesized particles is conducted using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The magneto-dielectric (MDL) coating over the antenna is done by mixing the ferrite powders with polyvinylidene fluoride (PVDF) polymer. The effects of the magneto dielectric layer on the monopole antenna’s performance are assessed in terms of return loss, radiation pattern, and impedance bandwidth using a vector network analyzer and an Anechoic Chamber. A significant improvement in the impedance bandwidth (400 MHz) is observed for the Mn-doped CoFe2O4–PVDF coating, achieving a bandwidth of 3.00 to 3.4 GHz. The antenna exhibits miniaturization with a resonance frequency shift to 3.2 GHz, achieving a peak gain of 2.6 dBi. The results demonstrate that the Mn-doped CoFe2O4–PVDF superstrate effectively supports antenna miniaturization for the sub-6 GHz frequency bands, such as n77 and n78, used in 5G applications.