Abstract: Mycotoxins, heavy metal ions, and pesticide residues present in grain and oil products pose potential threats to public health, highlighting the urgent need for the development of efficient and sensitive detection systems to ensure food safety. In this review, recent advances in electrochemical detection techniques for analyzing such contaminants in grain and oil matrices are systematically summarized. The application pathways for electrochemical sensing of mycotoxins, heavy metals, and pesticide residues are discussed, with particular emphasis placed on the integrated strategies involving ion-imprinted polymers, biomolecular recognition elements, and nanomaterial-modified electrodes for constructing functional sensing interfaces. Key technical breakthroughs in sensor configuration optimization, signal amplification mechanisms, and selective recognition are analyzed in the context of overcoming challenges posed by complex grain and oil matrices. Furthermore, current limitations—including sample matrix interferences, insufficient long-term stability, limited reusability, and high cost—are also discussed. Future research directions may focus on enhancing anti-interference capability, improving stability and reliability, and developing cost-effective sensor designs, to promote the practical application of electrochemical sensing technologies in grain and oil safety monitoring.