A method of modifying earthquake ground motion based on the wavelet transform is proposed, to take into account the effects of linear/nonlinear response spectra, frequency content, and ground motion energy. A wavelet-based procedure has been used to decompose recorded ground motion into finite wavelet coefficients, and then, with matrix processing, the coefficients have been suitably substituted and scaled to match the response spectra and total energy of earthquake ground motions. The proposed method has been verified by modifying five recorded accelerograms such that they are compatible with the same linear/nonlinear and energy spectra.