Abstract: A method for generating a heart organoid is provided. The method includes forming a cellular aggregate of pluripotent stem cells, activating Wnt signaling in the cellular aggregate to cause the cellular aggregate to differentiate into a three-dimensional cardiac mesoderm, and inhibiting the Wnt signaling in the cardiac mesoderm to form the heart organoid. The heart organoid includes myocardial tissue, endocardial tissue defining at least one chamber, and epicardial tissue disposed on at least an outer surface of the myocardial tissue. The heart organoid beats. Heart organoids prepared in accordance with the method are also provided.