Otomastoiditis caused by mycobacterial infections is uncommon and recalcitrant. Its clinical presentations, sometimes similar to those of common chronic suppurative otitis media, make diagnosis difficult. This retrospective study analyzed the clinical features, treatment course, and therapeutic outcomes of patients with mycobacterial otomastoiditis. The cases of six patients diagnosed with mycobacterial otomastoiditis or suspected mycobacterial infection between January 2007 and January 2019 in a single tertiary medical center in Taiwan were investigated. Information about predisposing factors, clinical features, culture reports, histopathology, treatment course, and outcomes were collected and analyzed. Relevant literature available in English was also reviewed. One patient was infected with tuberculous mycobacteria, two with suspected tuberculous mycobacteria, and three with nontuberculous mycobacteria. All six patients responded poorly to empiric antibiotic therapy, and diagnosis was not possible at their previous clinics. Five patients underwent tympanomastoidectomies; one was administered antimycobacterial medication without undergoing surgery. Mycobacterial infection was confirmed from a tissue culture or from the histopathology of the specimen, but in two patients, no definitive evidence of tuberculosis was found. Antimycobacterial medication was administered based on clinical suspicion, and improvement was noted. With appropriate therapy, all patients recovered, and no sequelae were observed after treatment. If empiric antibiotic therapy cannot achieve acceptable results, atypical infections, such as mycobacteria, should be considered. Antimycobacterial medication could be administered under clinical suspicion, serving as a diagnosis ex juvantibus. Surgical intervention might help reduce the bacterial load and obtain specimens for accurate diagnosis, but this may be unnecessary if appropriate antimycobacterial medication results in improvement. Early diagnosis and treatment can prevent complications in patients with recalcitrant otomastoiditis.