Salivary exosomes have emerged as a promising non-invasive liquid biopsy platform for the detection of both localized and distant malignancies. Tumour-derived exosomes originating from systemic cancers can enter systemic circulation, interact with salivary gland epithelial cells, and subsequently release tumour-associated nucleic acids and proteins into saliva. Recent studies have demonstrated that salivary exosomal miRNAs, mRNAs and proteins possess significant diagnostic potential for early-stage tumour detection, particularly in pancreatic cancer, lung cancer and oral squamous cell carcinoma (OSCC). Pilot studies in pancreatobiliary cancers identified elevated salivary exosomal miR-1246 and miR-4644 with combined diagnostic area under the curve (AUC) values of 0.833, whereas meta-analyses of saliva-derived miRNAs reported pooled sensitivity and specificity values of 87% and 86%, respectively, with pooled AUCs approaching 0.93. Lung cancer-associated salivary exosomal biomarkers including BPIFA1, CRNN, MUC5B and IQGAP1, together with mRNA panels comprising CCNI, EGFR, FGF19, GREB1 and FRS2, demonstrated high discriminatory accuracy for early-stage disease. In OSCC, salivary exosomal miRNAs including miR-21, miR-31, miR-155 and miR-200c consistently demonstrated AUC values exceeding ~0.89. Emerging biomarkers such as miR-10b-5p and miR-486-5p also exhibit promising diagnostic and therapeutic relevance in head and neck squamous cell carcinoma (HNSCC). Despite encouraging proof-of-concept evidence, substantial challenges remain, including lack of methodological standardization, limited cohort sizes, absence of population-scale prevalence studies and interstudy heterogeneity. Future translational advancement will require multicentre prospective validation studies integrating multi-omics biomarker panels and direct comparison with blood-based liquid biopsy approaches.