The effect of nonparabolicity on the transverse magnetoresistance of degenerate piezoelectric semiconductors in strong dc magnetic fields has been studied for the case where acoustic phonons are the dominant scattering mechanism. The calculation has been performed taking into account the inelasticities in the electron‐phonon scattering due to the finite energy of phonons involved. Results show that the transverse magnetoresistance due to the piezoelectric coupling for the nonparabolic band structure is enhanced much more considerably than that for the parabolic band structure. From our numerical results for the nonparabolic band structure, it can be seen that the piezoelectric coupling plays the same important role for the transverse magnetoresistance as the deformation‐potential coupling. We also found that the transverse magnetoresistance for both parabolic and nonparabolic band structures oscillates with the dc magnetic field owing to the degeneracy of the electron gas.