Selenium, an essential micronutrient for both animals and humans, has been documented to possess antimicrobial properties against a wide range of pathogenic microorganisms. One of the primary mechanisms by which selenium exerts its antimicrobial activity is through the generation of reactive oxygen species that can damage microbial cells. Besides its direct antimicrobial effects, selenium can enhance the immune response to infections, making it a potential tool in the prevention and treatment of infectious diseases. Given the growing threat of antibiotic resistance and the need for alternative therapeutic options, the antibacterial properties of selenium are of interest to the scientific community. This book chapter will summarize the current state of knowledge on the antibacterial properties of selenium, and its potential clinical applications as a therapeutic agent against infectious diseases. Further, the chapter explores the limitations and challenges associated with the use of selenium as an antibacterial agent.