Metal nanoparticles (MNPs) introduced in colorimetric sensing have gained considerable attention in various industrial applications, including food safety, environmental monitoring, medical diagnostics, due to their remarkable capabilities. This chapter reviews the current challenges, recent innovations, and future perspectives of MNP-based colorimetric sensors, with a focus on the detection of foodborne pathogen, chemical residues, and environmental toxins. Despite their advantages such as high sensitivity, rapid response, and ease of use, critical issues such as sensitivity, selectivity, reproducibility, and cost remain barriers to broader implementation. For this reason, novel synthesis approaches, including green synthesis methods and the development of bimetallic nanoclusters, are being explored to address these limitations and simultaneously enhance sensor performance. Moreover, the integration of artificial intelligence and machine learning is expected significantly advance sensor capabilities, enabling more precise detection and increased operational efficiency. This chapter outlines the recent development in MNP-based colorimetric sensing platforms and highlight their potential as miniaturized, real-time, portable detection systems for diverse applications.