The corrosion resistance of plasma electrolytic oxide (PEO) coatings is a function of its thickness, porosity and cracks, type of phases formed and their chemical stability. The presence of pores and cracks is very critical as permeation of the corrosive medium through them decreases the corrosion protective ability of the PEO coatings. Particle incorporation has been explored as one of the strategies to improve the corrosion resistance of PEO coatings. The particles preferentially incorporated at the pores and cracks of the PEO coating serves as a carrier thus preventing the ingress of the corrosive medium. Several other factors such as the type of particles and their concentration, conductivity of the particles, mode of incorporation, change in phase content, densification of the oxide coating following particle incorporation, dependence on the type of anions, process parameters, and surface modification of particles on the level of particle incorporation, could determine the corrosion resistance offered by the PEO composite coatings. This chapter elaborates on how these factors could influence the corrosion resistance of PEO composite coatings.