This study focuses on the synthesis, thermal and dielectric properties of sustainable bio-phenol viz. thymol based polybenzoxazines for applications including low dielectric, high dielectric and water repellent coating applications. By following a simple one-pot method four unique set of thymol benzoxazines were synthesized using varied nature of amines such as laurylamine (l), stearylamine (s), aniline (a), fluoroaniline (f), trifluoromethylaniline (t), cyclohexylamine (c), allylamine (aa), furfurylamine (ff), Jeffmine D230 (j), isophoronediamine (i), methylenebis cyclohexylamine (m), diaminodiphenylmethane (dm), p-phenylenediamine (pp) and diaminodiphenylether (de). The synthesized four set of thymol benzoxazines have been studied for range of applications viz., water repellent coating on cotton fabrics (CFs), low and high k insulation applications. Char yield value of poly(T-de) has been noted as 40% which is greater than the rest of the other synthesized thymol based polybenzoxazines. Amidst the different benzoxazines, highest water contact value (146°) was noticed for poly(T-t). Poly(T-t) coated cotton fabric (CCF) exhibits the super-hydrophobic behavior, which shows the water repellent value of 163°. The 15 wt% of palm-flower silica (PFS) reinforced poly(T-ff) composites showed the lowest dielectric constant value of 2.01 with loss factor of 0.0024. Similarly, high k value of 7.80 with loss factor of 0.0021 achieved for 15 wt% of C-gn incorporated poly(T-de). The results from the different studies, the developed thymol polybenzoxazines and composites exhibited an excellent thermal and dielectric properties, making them suitable for sustainable, versatile coatings and microelectronics applications.