In the present study, fully bio-based photocurable trifunctional benzoxazines derived from resveratrol were designed and characterized for multi-dimensional applications. The molecular structure was confirmed using ATR-FTIR and 1H-NMR spectral techniques. The curing temperature and thermal stability were thoroughly studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) respectively. Notably, in DSC analysis RE-dda exhibited the lowest curing temperature of 191 °C among the synthesised benzoxazines. All the synthesised polybenzoxazines exhibited good thermal stability and start degrading after 263°C. Under UV irradiation, intriguing photoisomerization phenomena was observed in the case of RE-ffa and RE-lee based benzoxazines. The photoluminescence behavior of the UV irradiated benzoxazines was studied using fluorescence spectroscopy and RE-oda displayed a Stokes shift value of 318. Further benzoxazines were reinforced with cashew nut shell cake ash (CNSA) with a view to attain a low value of dielectric constant and to enhance the thermal stability of the composites. An incorporation of 10 wt% CNSA contributes to a reduction in the value of dielectric constant to 1.66, accompanied with a minimal value of dielectric loss of 0.0017. Furthermore, the hydrophobic behavior of the polybenzoxazines, composites and poly(RE-ole) coated cotton fabric was evaluated using water contact angle measurement. Poly(RE-ole) exhibited an impressive water contact angle value of 146°. Moreover, poly(RE-ole) coated cotton fabric displayed enhanced value of water contact angle close to superhydrophobic value of 151°. Data obtained from different studies infer the developed benzoxazines can be considered for water repellent and microelectronics insulation applications.