The widespread usage of toxic chemicals and radionuclides for various industrial, agricultural, and nuclear activities poses significant risks to ecosystems and human health. These contaminants remain in the ecosystems, leading to bioaccumulation in food chains and other adverse effects on biodiversity and human populations. Traditional remediation methods, such as physical and chemical treatments, have disadvantages with reference to efficiency, cost, and long-term sustainability. So, to overcome the downside of remediation process, scientific community has harnessed the remarkable metabolic capabilities of geomicrobes to transform various chemical contaminants into stable mineral phases. Furthermore, these biogenic mineral phases exhibit compatibility with synergistic remediation approaches, thereby offering sustainable solutions for mitigating the risks posed by toxic chemicals and radionuclides in contaminated environments. This chapter consolidates insights from the available literature to explore the role of geomicrobes in the biomineralization of toxic chemicals and radionuclides.