An apparatus and method for power amplification in a wireless communication system are provided. The apparatus includes an envelope generator for generating an envelope signal from a Radio Frequency (RF) signal, a switching controller for generating a first switching control signal by delta-sigma modulating the envelope signal, and for generating a second switching control signal by amplifying an error signal obtained from a difference between an envelope signal restored by filtering the modulated envelope signal and an original envelope signal and an amplifier for outputting a first output signal by amplifying a phase signal according to the first switching control signal, for outputting a second output signal by amplifying the phase signal according to the second switching control signal, and for combining the first output signal and the second output signal. Thus, high efficiency and high linearity can be accomplished in the power amplification.