We present the case of a 14-year-old male patient referred to paediatric cardiology for the incidental finding of a cardiac murmur and initially diagnosed with asymmetric septal hypertrophic cardiomyopathy. Due to deterioration in his functional class (NYHA II/IV), he was admitted to our institution for further evaluation. A hyperechoic mass measuring 35.7 mm × 39.4 mm was identified in the interventricular septum, with central vascularisation and a significant obstructive gradient in the right ventricular outflow tract (112 mmHg). Cardiac magnetic resonance imaging confirmed a highly vascularised lesion, hyperintense on HASTE, T1, and T2 sequences, with an extracellular volume of 67%, consistent with a cardiac haemangioma. Coronary CT angiography demonstrated perfusion by a septal branch of the left anterior descending artery. Given the anatomical involvement and the low feasibility of surgical management, cardiac catheterisation with embolisation of the septal branch using an Interlock Coil occlusion device was performed. Post-procedure angiography confirmed complete occlusion. Cardiac tumours in paediatrics are rare and generally benign, with haemangiomas being one of the least common neoplasms. Diagnosis relies on non-invasive imaging techniques, with echocardiography and magnetic resonance imaging playing crucial roles. In this case, the combination of echocardiography, coronary CT angiography, and catheterisation allowed for a comprehensive characterisation of the lesion and the development of a therapeutic strategy while minimising risks. The patient remains stable under follow-up. This multidisciplinary approach optimises the management of paediatric cardiac tumours, enabling individualised therapeutic options.