Provided are photon counting apparatuses and methods, and radiographic imaging apparatuses configured to receive charge signals corresponding to incident radiation photons, and to count the incident radiation photons by using a plurality of counting bits, such that the counting changes only one counting bit from among the plurality of counting bits when the count value is increased by one. By using the photon counting methods, a data-change frequency of photon counting data corresponding to radiation photons is minimized while counting the radiation photons based on charge signals corresponding to input radiation photons.