Background: Oral mucositis is a common and debilitating side effect of concurrent chemoradiotherapy for head and neck cancers, significantly affecting patient quality of life and treatment continuity. Previous studies have highlighted the potential role of oral hygiene in mitigating the severity of mucositis, yet standardized care protocols remain underexplored. Objective: To investigate the relationship between oral hygiene and the incidence and severity of oral mucositis in patients undergoing concurrent chemoradiotherapy for head and neck cancers. Methods: A prospective observational study was conducted over six months at the Oncology Department of Combined Military Hospital, Rawalpindi, with a sample size of 100 patients. Patients aged 18-70 years with histopathologically confirmed head and neck cancers and an ECOG performance status of 2 or less were included. Oral hygiene was assessed using a standardized scale, and mucositis was graded post-therapy using the CTCAE version 5.0 criteria. Data were analyzed using SPSS version 25 with Chi-square tests and ordinal logistic regression. Results: The study found that 44% of patients with poor oral hygiene developed moderate to severe mucositis (grades 2 and 3), compared to 24% with grade 2 and 5% with grade 3 mucositis in the good oral hygiene group. The difference in mucositis severity between the two groups was statistically significant (P < 0.01). Conclusion: The maintenance of good oral hygiene is significantly associated with a lower severity of mucositis in patients receiving concurrent chemoradiotherapy for head and neck cancers. This association suggests that standardized oral care protocols should be an integral part of cancer treatment to improve patient outcomes.