Undeniably, research on thin films in recent decades has opened countless opportunities for the voluntary modification and manipulation of material properties through dimensionality modifications, defect engineering, and the formation of multifunctional heterostructures. These developments have yielded valuable applications in many fields, particularly those that contribute to detecting various parameters that enhance wellness, health, and quality of life. Therefore, this chapter will analyze thin film sensors from the perspective of their environmental and biological applications, as well as their advantages and contributions to scientific advances. Regarding environmental sensors, the emphasis will be on those that facilitate monitoring air quality (using gas sensors that detect different types of air pollutants such as hydrocarbons, nitrogen oxides, carbon monoxide, carbon dioxide, and other compounds), and water quality (monitoring various physical, chemical, and biological parameters). Regarding biological sensors, the discussion will cover optical sensors, glucose sensors, piezoelectric sensors, and immunosensors.