This paper presents a blind frequency offset estimation method for Polynomial Cancellation Coded Orthogonal Frequency Division Multiplexing (PCC-OFDM) systems. We have theoretically derived the frequency offset estimator. The estimation exploits the Subcarrier Pair Imbalance (SPI) which is presented in terms of the power difference between two demodulated subcarriers in a PCC-OFDM subcarrier pair. The estimator can be used for high order QAM modulation schemes. In all cases, the estimator has an approximately linear relationship with the frequency offset. The potential application of the estimator in conventional OFDM systems is also investigated in this paper.