Myasthenia gravis is an autoimmune disorder caused by the production of antibodies that block either acetylcholine receptors or structural receptors of the neuromuscular junction. There is expanding evidence that novel coronavirus (2019-nCoV) disease can lead to the development of an autoimmune response. Myasthenic crisis, a life-threatening respiratory muscle weakness severe enough to necessitate intubation or tracheostomy, can be a potential complication of myasthenia gravis. In this report, we describe the case of a 57-year-old man with acute respiratory insufficiency requiring emergency tracheostomy. His health condition rapidly deteriorated 1 week after initiating systemic corticosteroid treatment for a suspected adult-onset asthma exacerbation. The patient had a history of COVID-19 infection and thymectomy, which were noted in his medical records. Serological testing and electrodiagnostic evaluation confirmed the diagnosis of myasthenia gravis. The patient was treated with plasma exchange, continuous neostigmine infusion, and prednisone. He was successfully decannulated and discharged with anticholinesterase inhibitors and long-term immunosuppression therapy. It is important to consider neurological disorders in the differential diagnosis for patients presenting with respiratory insufficiency, particularly during the COVID-19 pandemic.