A semiconductor package includes a substrate and a plurality of semiconductor chips stacked on the substrate. Each of the semiconductor chips has a front surface, a rear surface opposite to the front surface, a sidewall surface connecting the front surface to the rear surface, a vertical through electrode extending from the front surface toward the rear surface with a predetermined depth, and a horizontal through electrode laterally extending from the sidewall surface to be connected to the vertical through electrode. At least one connection member is disposed on the sidewall surfaces of the semiconductor chips to connect the horizontal through electrodes of the semiconductor chips to each other. Related methods are also provided.