The present invention deals with the development of facile process route for cardanol based bisphenol-BC, trisphenol-VC, and tetraphenol-TC (card-polyphenols) by reacting sustainable bio-based cardanol with benzaldehyde, vanillin and terephthalaldehyde in the presence of combination of concentrated hydrochloric acid and sulfuric acid in the ratio of 2:1 (v/v) as catalysts at 80°C for 12 hours with yield of bisphenol-BC, trisphenol-VC, and tetraphenol-TC are 88, 85 and 83% respectively. The structural characterization of card-polyphenols was carried out using FTIR, NMR and Mass spectra. The card-polyphenols produced in the present invention are considered as vital precursors for production of industrial resins like epoxies, benzoxazines, cyanate esters, and urethanes for wide range of industrial applications. The card-bisphenol synthesized was converted in to benzoxazines by reacting with paraformaldehyde and selected representative amines and their thermal properties were studied. The polymerization (curing) temperature obtained for bisphenol-BC based benzoxazine representative samples namely BBC-a, BBC-aa, BBC-ffa, BBC-imp, BBC-oda and BBC-lfma are 228°C, 254°C, 260°C, 220°C, 253°C and 268°C, respectively. The present invention is considered as cutting-edge concept in the field of utilization of sustainable bio-phenolic cardanol for the possible replacement of fossil-based bisphenols in the production of polymeric products for wide range of industrial applications.