Given its high toxicity and widespread presence in the Earth's crust, arsenic, a metalloid, poses a significant threat to human health, mainly when consumed by contaminated water. In this chapter, we extensively examine the many oxidation states of arsenic, focusing specifically on the more dangerous forms, notably arsenite (As(III)) and arsenate (As(V)), along with the corresponding toxicological consequences. This paper reveals the limitations of conventional methods for removing arsenic. These processes often lead to the generation of hazardous by-products and are reported to be ineffective in natural environments. On the contrary, biological treatment methods such as bioremediation, biosorption, bioaccumulation, and phytovolatilization have emerged as viable alternatives that are efficient and ecologically sustainable. Microbial involvement is essential in these processes, as well as biotransformation and biomineralization, to mitigate arsenic toxicity and help remove arsenic from contaminated areas. This chapter explores the genetic foundation of arsenic biotransformation, emphasizing the crucial role of specific genes and microbial interactions in detoxification. Furthermore, it emphasizes the possibility of using these inherent processes to create novel and ecologically sound interventions to deal with arsenic pollution in different environmental settings.