Climate change has intensified the frequency and severity of drought and heat stress, posing a major challenge to global cereal production. Quantitative trait loci (QTL) mapping has emerged as a powerful tool for dissecting the genetic architecture of complex traits associated with abiotic stress tolerance in crops such as rice, wheat, maize, barley, and sorghum. This review highlights the advances in QTL identification, validation, and utilization for improving stress tolerance in cereals. We summarize key QTLs associated with drought avoidance, osmotic adjustment, root architecture, flowering time regulation, and grain yield under stress. The integration of traditional QTL mapping with genome-wide association studies (GWAS), marker-assisted selection (MAS), and genomic selection has accelerated the translation of discoveries into breeding programs. Despite these advances, challenges remain in the stability of QTLs across environments, epistatic interactions, and the need for high-throughput phenotyping to match genomic data. Future perspectives emphasize the role of multi-omics integration, genome editing, and pan-genomic resources in refining QTL-based breeding for climate-resilient cereals. By bridging molecular genetics with applied breeding, QTL mapping continues to play a pivotal role in ensuring food security under changing climates.