It is well known that a ZnO‐on‐Si structure supports two distinct surface waves, called the Rayleigh and the Sezawa modes, if the ZnO layer is sufficiently thick. Herein we report a unique surface wave resonator that operates by efficiently converting between the two modes at the resonant frequency. The mode conversion resonator promises enhanced out‐of‐band signal rejection since input and output coupling is effected through different modes.