<p>Grains undergo several biochemical changes during their post-harvest stages and are affected by various contaminants that can impact their quality. It is important to monitor the quality of grains throughout its supply chain and storage to maintain food safety, as it is a staple food for a large population worldwide. Several methods are there to monitor the quality of grains, but colorimetric methods are significant as they offer advantages such as high sensitivity, specificity, rapid detection, and cost-effectiveness, making them valuable tools for food safety monitoring. In this review, the role of colorimetric sensors in detecting various contaminants, including mycotoxins, heavy metals, and pesticides, as well as in the quantification of key nutritional components such as proteins, vitamins, and antioxidants, is discussed aiming at their applicability in grain quality assessment. The advancement in sensor technology, such as integrating smartphone-based detection methods, nanotechnology, and paper-based sensors has facilitated real-time and on-site analysis and addressed the growing demand for efficient and portable sensing solutions. Future directions in the field focus on improving sensor selectivity and sensitivity, prioritizing the development of robust, multifunctional sensors to meet the increasing demand for high-quality, contaminant-free grains.</p>