The highly (100) oriented (Pb,La)(Zr,Ti)O 3 (PLZT) films were successfully grown on (110) Al-doped ZnO (AZO) coated on (100) SrTiO 3 (ST) substrates using an RF magnetron sputter. The ferroelectric, dielectric, and optical properties of the transparent AZO/PLZT/AZO/ST structure were investigated to suggest the feasibility of AZO as an alternative transparent conductive oxide (TCO) electrode for optical devices requiring the longitudinal electro-optic (EO) effect. Recorded P-E loops showed slim hysteresis, and the remanent polarization and coercive field were 6.5¯C/cm 2 and 37 kV/cm. The relative permittivity and loss tangent were 745 and 0.044 at 10 kHz, respectively. The optical transmittance of the structure was over 90% in the near-infrared (NIR) region. Finally, the AZO/PLZT/AZO films grown on the ST substrate exhibited a strong quadratic EO effect and the longitudinal EO coefficient was 180 nm 2 /V 2 at = 1550 nm.