Single phase of La0.8Ba0.2Fe0.3Mn0.35Ti0.35O3 nanoparticles were successfully synthesized by mechanical alloying method. The mixture of all precursors were first mechanically milled for 10 hrs and then sintered at a temperature of 1000 °C for 10 hrs in which a fully crystalline material is ensured. The sintered material was then re-milled for 20 hrs to obtain powder-based nanoparticles. The refinement of x-ray diffraction trace for re-milled materials confirmed a single phase material with a monoclinic structure of lattice parameters: a = 5.5182(8) Å, b = 5.5442(8) Å and c = 7.822(1) Å, α = γ = 90° and β = 89.63(1)°. The mechanically alloyed and sintered materials in the first mechanical milling resulted in powders with mean size 521 nm. The mean size particle size were reduced further to 62 nm in the second mechanically milled powders. Results of mean crystallite size evaluation for respective powder materials showed almost similar mean crystallite size about 43 nm. In addition, the hysteresis curve showed that the sample is ferromagnetic. Results of VNA evaluation indicated that there were three of absorption peaks with reflection loss values ~ -9.0 dB, ~ -11.5 dB, and ~ -25.0 dB at frequency 9.9 GHz, 12.0 GHz, and 14.1 GHz respectively. The study concluded that the La0.8Ba0.2Fe0.3Mn0.35Ti0.35O3 material with nanoparticles has been successfully synthesized showing a good candidate as microwave absorbing materials.