Objective To investigate the changes and significance of serum immunoinflammatory indexes and 25-hydroxyvitamin D (25-OH-D) levels in patients with vestibular neuritis. Methods A total of 120 patients with vestibular neuritis admitted to the Third People's Hospital of Henan Province from June 2021 to June 2023 were selected as the study group, and 100 healthy people without vertigo or balance disorder who underwent physical examination in the same period were selected as the reference group to conduct a prospective study. Baseline data of the two groups of subjects were collected, serum immunoinflammatory indicators and 25-OH-D levels were detected and compared. Multivariate binary Logistic regression was used to analyze the risk factors of vestibular neuritis, and Pearson related software was used to analyze the correlation between serum 25-OH-D levels and immunoinflammatory indicators. Results There were no significant differences in age, sex and body mass index between the two groups (all P>0.05). Neutrophil/lymphocyte ratio (NLR), C-reactive protein (CRP) and CD8 ⁺ percentage were increased, while 25-OH-D, CD3 ⁺, CD4 ⁺ percentage and CD4 ⁺/CD8 ⁺ ratio were decreased in study group compared with reference group (all P<0.05). There were no significant differences in total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), immunoglobulin A (IgA), immunoglobulin M (IgM) and immunoglobulin G (IgG) between 2 groups (all P>0.05). Multivariate Logistic regression analysis showed that 25-OH-D and CRP were independent risk factors for vestibular neuritis (OR =1.125, 1.234, P<0.05). According to Pearson analysis, serum 25-OH-D level in vestibular neuritis patients was positively correlated with CD4 ⁺/CD8 ⁺ (r=0.518, P<0.05), but negatively correlated with CRP (r=-2.219, P<0.05). Conclusion Serum 25-OH-D level in patients with vestibular neuritis was significantly decreased compared with the control group. Both 25-OH-D and CRP were independent risk factors for vestibular neuritis, and serum 25-OH-D level in patients with vestibular neuritis was positively correlated with CD4 ⁺/CD8 ⁺, while negatively correlated with CRP. Vitamin D supplementation in patients with vestibular neuritis may be a new target for the treatment of this disease.