An apparatus for controlling a low voltage direct current (DC)-DC converter (LDC) for an eco-friendly vehicle includes a reference current receiver for receiving a reference current, a ramp signal generator for generating a ramp signal by overlapping an input current of the LDC, and a DC offset and a sawtooth wave for adjusting a gradient of the ramp signal, and a comparator for generating a pulse width modulation (PWM) signal using the reference current received by the reference current receiver and the ramp signal generated by the ramp signal generator.