The advent of immune checkpoint inhibitors (ICIs) for cancer therapy has heralded increasing frequency of immune-related adverse events including endocrinopathies, hepatitis, colitis and rarely myocarditis and myasthenia gravis (MG). The heterogeneity in clinical presentations regardless of organ-specific involvement can lead to delayed recognition and management of these events and adverse health outcomes. We describe a case of ICI-induced subclinical focal myocarditis that was recognised and treated in the broader context of MG. It is essential that patients with ICI-induced MG should be screened and monitored for myocarditis, a potentially fatal complication.