This paper proposes an accurate empirical vibration synthesis methodology for the vibration response of electric machines. The proposed method enables designers of the electric machines to synthesize the vibration response of mechanical components that are connected to the electric machine's stator, for given magnetic force profiles. It utilizes the experimentally obtained structural transfer functions by vibration testing, and the magnetic forces computed by magnetostatic finite element analyses. The proposed method has been applied to synthesize vibration responses of an interior permanent magnet machine. The synthesized vibration response agrees very well with the measured vibration response for a wide frequency range and various rotational speeds.