Background Pembrolizumab, an immune checkpoint inhibitor (ICI), has revolutionized the cancer treatment for many types of malignancy, including metastatic urothelial cancer . As pembrolizumab used becomes popular, the understanding of the associated potential adverse events is important. Method A case of urothelial cancer of bladder with local recurrence received pembrolizumab therapy then had neurological adverse events was reported, and relevant literature was reviewed. Results We presented a 79-year-old male with urothelial cancer of bladder with local recurrence after operation and traditional therapy. He received pembrolizumab therapy just half dose due to old age. 21 days later, he developed an acute hepatitis. 26 days after the first infusion of pembrolizumab, he had chest pain and progressive bilateral ptosis. 3rd -degree atrioventricular block was found then he received pacemaker insertion. Further neurophysiological study confirmed diagnosis of myasthenia gravis and myositis. He received intravenous methylprednisolone and immunoglobulin infusion and pyridostigmine bromide therapy but he still needed intubation and mechanical ventilation 28 days after pembrolizumab. Conclusion Pembrolizumab may induce rare severe neurological and cardiovascular adverse effects. A prompt comprehensive investigation to ascertain the presence of IM3OS are crucial for early diagnosis.