Congenital long QT syndrome (LQTS) is a genetic disorder causing prolonged QT intervals and an increased risk of arrhythmias and sudden cardiac death. With 25% of cases lacking known genetic mutations, diagnosis and treatment can be challenging. We present a successfully managed case of late-onset genotype-negative phenotype-positive LQTS presenting as palpitations, complicated by a single event of polymorphic ventricular tachycardia, followed by a review of the literature. This case underscores the gaps in understanding congenital long QT syndrome, especially in genotype-negative cases, and highlights the need for ongoing research for risk assessment and effective management to prevent fatal cardiac events.