The prime objective of hybridizing DGEBA epoxy resin with bio-based benzoxazine, bi-functional benzoxazine. and bio-silica is to exploit the inherent characteristics (thermal stability, flame retardant behaviour, weather resistance and hydrophobic behaviour) of sustainable bio-materials to replace petroleum based insulating materials for better performance and enhanced longevity. The bio-based benzoxazines has been synthesized using sustainable bio-phenolic precursor material namely cardanol with aniline and formaldehyde through a facile process route in the absence of any solvents and its properties were characterized using modern analytical techniques. The cardanol based mono-functional and bisphenols based bi-functional benzoxazines were synthesized in the present invention have been hybridized with DGEBA epoxy resin reinforced with an appropriate, quantity of 3-gIycidoxypropyltrimethoxy functionalized bio-silica derived from rice husk in order to archive lower dielectric constant and thermal conductivity with enhanced breakdown voltage. The properties of hybridized composites namely tensile strength, flexural strength, thermal conductivity, dielectric constant, breakdown voltage were tested by appropriate experimental methods, to assess their suitability towards electrical insulation applications. Data obtained from different studies, it was observed that the lowest value of dielectric constant of 1.76 and the highest value of break down voltage of 47kV were obtained for" the hybrid composite sample having the composition of C-a/BF-afOGEB A/bio- silica (1:1:1:3). Further, the different hybridized bio-composites developed in the present invention possess an enhanced thermal stability, flame retardancy, mechanical strength and improved dielectric behaviour and are found to be suitable for medium voltage electrical insulation application.