Emergency surgery in adults with congenital heart disease (ACHD) is uncommon, but presents exceptional complexity due to diverse anatomy, prior interventions and comorbid conditions. This chapter reviews the principal indications, surgical strategies and perioperative considerations in the emergent management of ACHD patients. Key clinical scenarios include fulminant infective endocarditis with haemodynamic instability, aortic emergencies, acute decompensated heart failure and complications arising from percutaneous interventions. Additional sections address the challenges of emergency re-sternotomy, pacing in complex anatomy and surgery during pregnancy. The chapter highlights the importance of meticulous preoperative assessment, multidisciplinary decision making and tailored use of mechanical circulatory support, including extra-corporeal membrane oxygenation and ventricular assist devices. Risk prediction models such as the PEACH score are discussed within the context of perioperative mortality and comorbidity burden. Despite high procedural risk, outcomes continue to improve through advances in imaging, surgical technique and postoperative care. Ultimately, successful emergency surgery in ACHD relies on collaboration across the disciplines to deliver safe, individualised and timely interventions in this high-risk patient population.