In a variety of applications, including medication delivery, tissue engineering, imaging diagnostics, and biosensors, bio responsive nano systems are becoming more and more significant. Among these, pH-responsive delivery systems have drawn a lot of interest due to their capacity to react to the microenvironment of disease and release therapeutic medications in reaction to pH. This review paper discusses four different types of pH-responsive modes, their corresponding design methodologies, applications, and future directions by cleverly designing pH-sensitive nano systems for precision imaging or therapy. This is done in light of the significance of pH-sensitive nano-delivery systems.