Leveraging the quantum information-processing ability of superconducting circuits and long-distance distribution ability of optical photons promises the realization of complex and large-scale quantum networks. In such a scheme, a coherent and efficient quantum transducer between superconducting and photonic circuits is critical. However, this quantum transducer is still challenging because the use of intermediate excitations in current schemes introduces extra noise and limits bandwidth. We realize direct and coherent transduction between superconducting and photonic circuits based on the triple-resonance electro-optic principle, with integrated devices incorporating both superconducting and optical cavities on the same chip. Electromagnetically induced transparency is observed, indicating the coherent interaction between microwave and optical photons. Internal conversion efficiency of 25.9 ± 0.3% has been achieved, with 2.05 ± 0.04% total efficiency. Superconducting cavity electro-optics offers broad transduction bandwidth and high scalability and represents a significant step toward integrated hybrid quantum circuits and distributed quantum computation.