Corrosion remains a major industrial challenge, compromising material durability and generating substantial economic costs. Conventional hexavalent chromium (Cr(VI)) compounds provide active protection but face restrictions due to toxicity. Hybrid organic–inorganic sol-gel coatings offer a versatile platform for chromate-free corrosion protection. This work investigates the physicochemical characteristics and corrosion performance of a cerium-containing hybrid organic–inorganic sol-gel coating based on 3-mercaptopropyltrimethoxysilane (MPTS). To enhance environmental sustainability, the coating was formulated with 60 vol.% alcohol, compared with ≈95 vol.% in literature benchmarks, and incorporated 5 wt.% cerium, reducing volatile organic compound use while eliminating Cr(VI). Chemical structure, morphology, elemental distribution, adhesion, cerium release, and electrochemical performance were evaluated by ATR-FTIR, SEM- EDS, an ASTM D3359- adapted cross-hatch test, ICP-MS, and EIS. ATR-FTIR confirmed polysiloxane network formation, while SEM-EDS revealed a homogeneous surface distribution of cerium-containing nodules. The coating achieved a 4B adhesion rating and sustained cerium release of 21.2 µg after 1 week in 3.5 wt.% NaCl. EIS demonstrated a low-frequency impedance modulus of 9.03×10⁵ Ω⋅cm² after 1 week and improved electrochemical response in artificially damaged coatings versus Ce-free control. Combined adhesion, sustained cerium release, and electrochemical protection highlight this sustainable hybrid sol-gel formulation for high-performance chromate-free corrosion protection.