Double-inlet left ventricle (DILV) is a rare congenital cardiac abnormality that is a subtype of univentricular congenital disease. This defect has been reported in people and large animals but has not been previously described in a small animal. Here, we report a one-year-old cat diagnosed with DILV accompanied by a hypoplastic right ventricle and ventricular septal defect. Complete echocardiography, fluoroscopy with non-selective angiography, and computed tomography with angiography were used to document and characterize this rare case presentation. Findings in this patient showed similarities to previously documented cases of DILV in a calf and foal and were most consistent with type I Holmes classification of DILV in people.