Cyclodextrin plays an integral part in the host–guest chemistry of supramolecules by encapsulating the guest in its hydrophobic cavity. These encapsulations can remarkably modify the physical, chemical, and/or biological properties of the guest molecules. This chapter emphasises the applications of cyclodextrin coatings either in sol–gel or as a composite hybrid matrix with nanoparticles. The solubility of sparingly soluble organic compounds (inhibitor/drug as a guest) is increased by encapsulation in the host cavity. These reversible complexes have shown a great effect in the field of corrosion and biofouling by on-demand slow release, thereby extending the time and enhancing the self-healing of the barrier passivating films. Salient aspects in these areas are discussed in this chapter.