Environmental pollution is adversely affecting our ecology, human health, and economy, and it is now a global concern. There are various forms of pollution, such as pollution of the air, soil, and water. Both living and nonliving systems are being harmed by various hazardous chemicals, such as heavy metals and organic pollutants. Techniques and instruments for the identification and elimination of these pollutants are urgently needed. For detection objectives, two primary methods have historically been employed: spectrometry and chromatography. The biggest disadvantages of these technologies include the requirement for highly qualified personnel, lengthy turnaround times, expensive equipment, and many more. Carbon-containing nanosensor is the best tool for the quick, highly selective and sensitive indication, and elimination of toxic pollutants from air, water, and soil. Different carbon-based elements are used in this process such as graphene, carbon nanotubes (CNTs), fullerenes, and carbon dots. There are many useful properties of the carbon-based nanosensors such as their high electrical conduction, large surface area, and unique functionalization characteristics. This chapter will provide you with the working principle, synthesis methodologies, and useful applications of carbon-based nanosensors for detection of toxic heavy metals, organic pollutants, and other gaseous toxic compounds. Wearable and portable systems can be developed to track the performance of carbon-based nanosensors. Carbon-based nanosensors can also be merged with some advanced AI-based technologies for the real-time assessment of their function and improved efficiency.