Metallic materials have been used as antibacterial agents since antiquity. Gallium (Ga), an abiogenic metal, has shown pharmaceutical effects in developing unconventional anticancer and antibacterial drugs. Recent advances have disclosed the potential of Ga-based materials in creating bactericidal medicine (GaBM) that is safe, efficacious, multifunctional, and even smart, showing promising results both in the lab research and in clinical trials. Here, we describe the chemical and toxicological principles underlying the antibacterial activity of various types of GaBM, including ions, colloids, and composites, and discuss their in vitro and in vivo performances in different disease models. We expect that GaBM is rapidly advancing towards broad-spectrum antimicrobial medicine in combating bacterial pathogens, fungi, and viruses, and other microorganisms; interdisciplinary research is on the way to improve molecular levelled understanding of GaBM and facilitate its future collaborations with drug discovery, nanotechnology, and precision medicine. Our study offers a comprehensive guidebook for the design, fabrication, and implementation of GaBM, which could benefit a wide range of communities including chemists, material chemists, and drug engineers working on developing next-generation antimicrobial materials, medications, and devices.