ObjectivesThe impact of rheumatic diseases, long‐term medication, and vaccination on COVID‐19 severity remain insufficiently understood, hindering effective patient management. This study aims to investigate factors influencing COVID‐19 severity in Chinese rheumatic patients and to provide real‐world evidence for patient care.MethodsWe conducted a retrospective observational study consisting of two cohorts, followed by a nested case–control analysis. The outpatient cohort included non‐severe COVID‐19 patients, while the inpatient cohort included consecutive severe COVID‐19 inpatients. Additionally, rheumatic patients from both cohorts were included for the nested case–control study. Clinical information was obtained from electronic medical records and surveys.ResultsA total of 749 outpatients and 167 inpatients were enrolled. In the outpatient cohort, rheumatic diseases were identified as a risk factor for the severity of dyspnea (No rheumatic disease: OR = 0.577, 95% CI = 0.396–0.841, p = .004), but not for mortality, length of hospitalization, or hospitalization costs in the inpatient cohort. Long‐term glucocorticoids use was identified as an independent risk factor for severity of dyspnea in rheumatic patients (OR = 1.814, 95% CI = 1.235–2.663, p = .002), while vaccination and immunosuppressant treatment showed no association. Vaccination was identified as a protective factor against hospitalization due to COVID‐19 in patients with rheumatic diseases (OR = 0.031, 95% CI = 0.007–0.136, p < .001), whereas long‐term glucocorticoids and immunosuppressant treatment showed no association.ConclusionsRheumatic diseases and long‐term glucocorticoids use are significant risk factors for COVID‐19 severity in the Chinese population, whereas emphasizing the protective effects of vaccines against COVID‐19 severity is crucial. Additionally, the investigation provides preliminary support for the concept that long‐term immunosuppressant therapy does not necessarily require additional prescription adjustments.