This chapter provides a comprehensive overview of recent developments and applications in the field of biosensors tailored for toxic gas sensing. Biosensors, leveraging the specificity and sensitivity of biomolecular recognition elements, play a pivotal role in the continuous evolution of gas sensing technology. The diverse range of biomaterials employed in biosensors, including enzymes, antibodies, DNA, and whole cells, each tailored to detect specific toxic gases with heightened precision. Emphasis is placed on the advancements in sensor design, fabrication techniques, and signal transduction mechanisms, which collectively contribute to the enhanced selectivity and sensitivity of biosensors. Additionally, it also addresses the challenges encountered in toxic gas sensing applications, such as cross-reactivity and environmental factors, and discusses innovative strategies employed to overcome these hurdles. The applications of biosensors in various industries, ranging from industrial safety to environmental monitoring, are highlighted, underscoring the critical role these devices play in mitigating risks associated with toxic gas exposure. This chapter is a valuable resource for researchers, engineers, and practitioners involved in advancing biosensor technology by providing insights into the current state of the field and avenues for future research.