The future of benzoxazine research focuses on achieving a delicate balance between low curing temperatures and sustainability without compromising material performance. Advancing their molecular design to optimize these properties enables the way for advanced materials suitable for applications in coatings, adhesives, and advanced integrated circuits. Thus, in this study, sulfur-containing thiol-modified benzoxazines (-SH) were synthesized using 3-mercaptopropanehydrazide (MH) and different phenolic precursors such as bis-thymol, phenol, cardanol, guaiacol, eugenol, thymol, furfural bis-thymol, bis-thymol, and trifunctional thymol-containing phenol. All of the samples were characterized for their structural and thermal properties using techniques such as 1H NMR, 13C NMR, DSC, and TGA. Among the systems studied, C-MH exhibited the lowest curing temperature of 174 °C, while poly(TTP-MH) showed the highest thermal stability with a char yield of 40% at 850 °C. Electrochemical studies, including Tafel and Nyquist plots, revealed that all polybenzoxazines possess excellent anticorrosion properties, with poly(TTP-MH) exhibiting higher efficiency than the rest of the coated specimens. Dielectric measurements further exhibited that these materials possess low dielectric constants and minimum loss values, making them suitable for advanced electronic applications. The results of antimicrobial studies reveal that TTP-MH acts a good microbial agent. Also, neat polybenzoxazines and their coated cotton fabrics exhibited good hydrophobic nature. Data from this work bring out the potential of biobased sulfur-modified benzoxazines as next-generation materials for high-performance applications. By reducing the curing temperature and enhancing material properties, it addresses antimicrobial, anticorrosion, and dielectric properties by contributing to a sustainable future in polymer science.