The impact of SARS-CoV-2 infection in patients with autoimmune/auto-inflammatory rheumatic diseases (AARD) under immunomodulatory treatment has been a focus of interest during the COVID-19 pandemic. In this observational study, demographic data, disease related features and comorbidities, COVID-19 manifestations and outcome as well as antibody responses to SARS-CoV-2 were recorded among 77 consecutive patients with underlying AARD infected by SARS-CoV-2. Analysis of data was performed using univariate and multivariate models. Most patients (68.8%) had a mild COVID-19 course. The predominant clinical manifestations were fatigue (58.4%), low grade fever (45.4%) and upper respiratory tract symptoms (68.8%). About a quarter of patients required hospitalization (23.3%) and the mortality rate was 1.3%. Regarding COVID-19 severity, prior treatment with corticosteroids, mycophenolate mofetil or rituximab was more common in patients who developed a more serious disease course (60.0 vs 29.9%, p = 0.003, 40.0 vs 7.5%, p = 0.003, 10.0 vs 0.0%, p = 0.009, respectively). When disease related features and comorbidities were considered in multivariate models, older age and lung disease in the context of the AARD were found to be independent predictive factors for hospitalization (OR [95%]: 1.09 [1.03–1.15] and 6.43 [1.11–37.19]). Among COVID-19 related features, patients with shortness of breath and high-grade fever were more likely to get hospitalized (OR [95%]: 7.06 [1.36–36.57], 12.04 [2.96–48.86]), while anosmia was independently associated with lower hospitalization risk (OR [95%]: 0.09 [0.01–0.99]). Though the majority of AARD patients displayed a mild COVID-19 course, certain underlying disease features and COVID-19 related manifestations should prompt alertness for the physician to identify patients with AARD at high risk for severe COVID-19 and need for hospitalization.