In this work, we report a highly linear quantum well Mach-Zehnder (MZ) intensity modulator. The MZ modulator's linearity was enhanced by canceling the nonlinearities from the MZ interferometer and the nonlinear phase modulation. The MZ modulator demonstrated over 24 dB improvement in nonlinearity distortion level compared with that of a LiNbO3 MZ modulator. It achieved a third-order intercept point in phase perturbation of 2 π RMS. This is sufficient to allow an RF/photonic link to achieve over 120 dB·Hz2/3 spurious-free dynamic range (SFDR) with low photocurrent (<5 mA).