Ultraviolet (UV) radiation offers a nonchemical approach to microbial inactivation for disinfection and infection management. This chapter provides an overview of the antimicrobial activity of UV radiation, from its historical development to current applications. It examines the basic mechanisms by which the different UV wavelengths (UVC, UVB, and UVA) exert antimicrobial effects, focusing on the different properties and applications of each spectral range. Factors that influence the efficacy of UV disinfection include microbial properties, environmental conditions, and operating parameters. Applications include the disinfection of water, surfaces, and air, particularly useful in the healthcare sector. The role of UV radiation in combating bacterial, viral, fungal, and parasitic infections will be analyzed based on historical and current evidence. Emerging applications include far-UVC radiation for ongoing disinfection in inhabited areas, combined UV wavelengths, and synergistic approaches that integrate UV with other antimicrobial agents. This analysis will provide researchers, healthcare professionals, and engineers with up-to-date knowledge and prospects for using UV radiation in disinfection and infection control.