A method and apparatus for controlling a fusing temperature, and an image forming apparatus are provided. In the method of controlling a fusing temperature, power is supplied to a heat source included inside a heat roller at on/off chopping rates determined according to the temperature of the heat roller during a time period in which the temperature of the heat roller is rising, and power is supplied to the heat source at on/off chopping rates which are respectively increased by a predetermined value with respect to the determined on/off chopping rates during a time period in which the temperature of the heat roller is falling. Accordingly, a fusing property can be prevented from degrading in an initial printing process after a cold start occurs in a fusing unit, and thus a first print out time (FPOT) can be reduced.