Patients with rheumatoid arthritis (RA) who receive anti-tumor necrosis factor-alpha (anti-TNF-α) therapy are at increased risk of tuberculosis (TB), particularly extrapulmonary and disseminated TB. Although baseline TB screening is routinely performed prior to treatment initiation, active TB may develop during therapy. Here, we report the case of a 37-year-old woman with long-standing RA who developed disseminated TB three months after starting adalimumab, despite negative baseline chest radiography and interferon-gamma release assay results. The patient presented with prolonged fever, abdominal distension, and poor appetite. On assessment, pulmonary nodules, ascites, and peritoneal nodular lesions were identified. Histopathological examination revealed granulomatous inflammation with caseous necrosis, and polymerase chain reaction confirmed Mycobacterium tuberculosis infection. This report presents the clinical course of this patient and discusses the limitations of current TB screening strategies and the importance of ongoing clinical vigilance during anti-TNF-α therapy.