This chapter concisely explains the catalytic and battery materials applications of plasma electrolytic oxidized (PEO) metals and alloys. The adherent oxide layers developed by PEO on metal supports have attracted significant attention in catalysis research. The catalytic activity of the developed oxide layer can be boosted by various approaches, such as doping and heterojunction formation via in situ integration or post-impregnation of the active components. This chapter discusses PEO-derived electro-, photo-, and photoelectro-catalysts in different applications. PEO-derived anode electrode materials for lithium-ion batteries are also discussed.