A group of congenital heart disease (CHD) known as univentricular atrioventricular connections is characterized by the fact that only one ventricular cavity is capable of maintaining systemic and pulmonary circulations, and the other ventricle is a rudimentary chamber that lacks one or more of its components. These cardiac diseases are generally critical during the neonatal period due to the fact that the majority of these hearts have obstructions in the outflow tracts, which can result in pulmonary or systemic circulation being dependent on the ductus arteriosus. The diagnosis on fetal echocardiography is evident in the four-chamber view; however, a comprehensive evaluation of the fetal heart is required due to the concomitant cardiac lesions. The utilization of advanced technology is crucial for a comprehensive assessment of the fetal heart in the presence of this complex cardiac condition. Advanced three- and four-dimensional (3D and 4D) ultrasound technology aid in the comprehensive assessment of univentricular hearts. In this group of CHD, the optimization of neonatal and obstetric care is achieved through the use of precise prenatal diagnosis. This chapter will cover the topics of morphology, epidemiology, fetal echocardiography features, perinatal care, surgical approach, and prognostic variables of severities, focusing on prenatal diagnosis. This set of cardiac illnesses includes the following conditions: double-inlet ventricle, absent atrioventricular connection, and common inlet atrioventricular connection.