The book chapter deals with the significance of surface passivation and surface treatment methods in enhancing coatings’ performance, durability, and adhesion. Surface passivation involves forming a protective layer on material surfaces to deter corrosion and environmental deterioration. Chemical, electrochemical, organic, and inorganic techniques can be employed, each offering distinct advantages tailored to specific applications. Surface treatment encompasses mechanical, chemical, and physical procedures to prepare substrates for coating application. Mechanical treatments like abrasive blasting and grinding enhance surface roughness for improved mechanical interlocking. Chemical treatments such as acid etching and alkaline cleaning boost surface energy and cleanliness, while physical methods like plasma treatment, ion implantation, and laser surface treatment alter surface properties to enhance coating adhesion and performance. The chapter investigates how these processes heighten coating adhesion, prevent corrosion, and strengthen wear resistance. It also explores characterisation and evaluation methods like surface energy measurement, chemical analysis, topographical analysis, and adhesion testing to gauge treatment effectiveness. Real-world examples from the aerospace, automotive, and electronics sectors demonstrate the practical applications and advantages of surface passivation and treatment techniques. The chapter concludes by examining current obstacles and prospects, emphasising the necessity for eco-friendly and sustainable practices and technological advancements to meet the evolving demands of diverse industries. The comprehensive overview underscores the critical role of surface passivation and treatment in ensuring optimal performance and longevity of coating materials.