Tri-substituted cardanol based benzoxazine with functionalized rice husk ash (CBz/FRHA) bio-composites were developed using renewable resource materials, and their thermal, electrical, and biological properties were studied by different analytical methods. The molecular structure of CBz was confirmed by nuclear magnetic resonance (H-1 NMR) and Fourier transform infrared spectroscopy (FT-IR) techniques. Data resulted from thermal studies indicated that the incorporation of bio-based silica reinforcement effectively improved the thermal properties including T-g, thermal stability and char yield. Dielectric studies indicate that the bio-based composites possess the lower value of dielectric constant (low k-2.15) than that of neat matrix (low k-4.04). Further, the antimicrobial studies were carried out against Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae and Streptococcus bacteria using disk diffusion method and the results obtained confirm that the CBz/FRHA bio-composites possess an improved antibacterial behavior. Data resulted from different studies, and it is suggested that CBz/FRHA based bio-composites can be used as cost competitive materials in the form of adhesives, sealants, encapsulants and matrices for low-k insulation application in the field of microelectronics for high-performance applications.