Aims: Submandibular gland (SMG) removal is traditional performed during level 1B neck dissection for oral cavity squamous cell carcinoma (OCSCC). Although oncological outcomes are validated, there is limited information on functional outcomes. This systematic review evaluates functional or survival outcomes of SMG preservation versus conventional SMG-sacrificing neck dissection. Methodology: This review was registered prospectively on PROSPERO CRD420251038892. Systematic review of MEDLINE, Embase, Scopus, CINAHL, and grey literature from inception to April 2025 based on MeSH terms pertaining to “Submandibular gland” and “Neck dissection”. All studies examining SMG-preserving neck dissection in OCSCC were included. Primary outcomes of interest were functional outcomes (xerostomia, speech, voice). Risk of bias was assessed with ROBINS-I. Results: Of 439 studies, five studies met inclusion criteria, with 421 patients (194 SMG-sparing, 228 SMG-sacrificing). Xerostomia outcomes were reported in all studies; two demonstrated statistically significant improvement in salivary function with SMG preservation, and two found no sustained difference. Speech and swallow outcomes were reported in one study each, suggesting improvement in both. One study reported improved swallowing scores, with no significant difference in speech outcomes. Study quality was at moderate to serious risk of bias, with small sample sizes and methodological heterogeneity precluding meta-analysis. Conclusion: SMG-sparing neck dissection may reduce xerostomia following neck dissection for OCSCC. Further research on swallowing or speech outcomes is required to make further recommendations. Standardised prospective studies using validated patient-reported outcome measures and international collaborations are required.