This study critically examines the influence of serum 25-hydroxyvitamin D [25(OH)D] levels on the health-related quality of life among Chinese adults diagnosed with allergic rhinitis. An observational research design incorporating structured questionnaires was employed to collect data. The investigation monitored the clinical status of individuals with confirmed allergic rhinitis and assessed how variations in serum 25(OH)D levels corresponded with changes in their health-related questionnaire. A total of 131 eligible participants who met the inclusion and exclusion criteria voluntarily completed the survey. The results indicate a moderate negative correlation between serum 25(OH)D levels and symptom severity, suggesting that higher vitamin D levels are associated with improved health-related quality of life outcomes. Participants with sufficient serum 25(OH)D levels reported reduced symptom burden compared with those exhibiting vitamin D deficiency. The study further demonstrates that approximately 17.6% of the variance in health-related quality of life can be predicted by serum 25(OH)D levels, underscoring the clinical significance of vitamin D status in allergic rhinitis management. Although the strength of association is moderate, the findings highlight the potential of optimising vitamin D levels to mitigate disease severity and enhance quality of life in affected individuals.