This study presents a facile, clean route of fabrication of an eco-friendly, hydrophobic, and high solid (75.5 %) Cardanol-derived nano-dispersed waterborne polyurethane (WBPU) coatings to mitigate mild steel corrosion. The absence of additional crosslinkers and the use of green chemistry principles to develop WBPU nano-dispersions make the process feasible and environmentally benign. The impact of the variation in the amine content (10-25 %) was observed on the physical, chemical, and corrosive properties of the nano-dispersed WBPU coatings. FTIR analysis confirmed the chemical structure and curing of WBPU, while the crosslinking density indicated the formation of a protective coating surface. Transmission electron microscopy (TEM) analysis revealed the presence of uniform spherical nano-dispersions of size 7 +/- 3 nm. A strong correlation was observed between Dynamic light scattering and TEM analysis, confirming uniform nano-dispersion with long-term stability. X-ray diffraction and scanning electron microscopy analysis demonstrated an amorphous surface with dense and rough morphology, with spherical nanostructures. Atomic force microscopy studies reveal a surface with moderate nano-roughness with a balanced distribution of peaks and valleys. Physico-mechanical testing showed excellent performance across all compositions, with high scratch hardness (2 kg), impact resistance (passes 150 lb./in.), bending flexibility (passes 1/8 in.), 100 % crosshatch adhesion, gloss, and wear resistance. Chemical resistance (3.5 % HCl, NaCl, NaOH, ethyl methyl ketone, and water) showed no significant changes, confirming durability. Overall, the composition with 20 % amine exhibited superior performance, featuring high hydrophobicity and thermal stability up to 230 degrees C. Electrochemical impedance spectroscopy in 3.5 % NaCl for 24 days demonstrated exceptional corrosion inhibition efficiency (98.98 %), corrosion protection, low corrosion rates, and excellent barrier properties. Cardanol-based WBPU nano-dispersion coatings and their formulation offer a sustainable, high-performance alternative protective polymeric material for various applications.