Living organisms increasingly grapple with the impact of rapid environmental changes, including climate shifts, pollution, and resource scarcity. To effectively address these challenges, advanced monitoring tools are essential. Traditional methods like gas chromatography, high-performance liquid chromatography, and mass spectrometry, while effective, suffer from high costs, time-intensive procedures, and reliance on specialized equipment and expertise. In this context, nanoparticle synthesis technology emerges as a promising solution. By precisely controlling size, shape, and properties at the nanoscale, it enables the development of advanced sensors. These nanosensors offer rapid response times, heightened sensitivity, and selectivity, making them ideal for accurate environmental and health monitoring. Nanomaterials (NMs), with their unique attributes, such as a high surface area-to-volume ratio and exceptional electronic, optical, and mechanical properties—outperform traditional methods in detecting minute quantities of contaminants and environmental fluctuations. This chapter explores the use of bismuth chalcogenides nanostructures in sensing applications. It covers synthesis methods, sensor fabrication, and characterization techniques, highlighting bismuth chalcogenides such as Bi2S3, Bi2Se3, and Bi2Te3 for their high carrier mobility, extensive surface area, and tunable properties, making them promising candidates for cost-effective, sensitive sensors.