Background Alopecia areata (AA) is an autoimmune disorder and chronic recurrent inflammatory disease that results in non-scarring hair loss. Objectives Our aim is to investigate several parameters related to autoimmunity and inflammation in AA patients and to evaluate their association with this disease. Methods This study included a total of 672 eligible AA patients and 580 age- and sex-matched healthy individuals who were treated at a third-class hospital in Hefei from January 2016 to May 2020. Data for serum C-reactive protein (CRP), 25-hydroxy vitamin D (25(OH)D), T3, T4, thyroid-stimulating hormone (TSH), thyroid antibodies (TPOAbs and TGAbs), antinuclear antibodies (ANA), complements (C3, C4), and several immunoglobulins (IgA, IgM, and IgG) were collected in this study. Results Regarding autoimmune-related functional indicators, there were no statistically significant differences between TSH, TGAbs, C3, C4, IgA, IgM, and IgG levels between AA patients and healthy controls. Only T3, T4, TPOAbs, and ANA values were significantly abnormal in the AA group compared with the healthy individuals (p < 0.05). In addition, the mean serum 25(OH)D concentration was significantly lower in the patient group than that in control group (p < 0.05), and serum CRP was significantly increased (p < 0.05). Conclusion Although the etiopathogenesis of AA is not clear, the importance of monitoring the levels of T3, T4, TPOAbs, ANA, and 25 (OH)D in AA cases is indispensable.