In this research, the effects of ZnO modification on ferroelectric order of Pb (Mg1/3Nb2/3)0.9Ti0.1O3 (PMNT) ceramics were studied through characterizations of dielectric and ferroelectric properties. The PMNT/xZnO (where x = 0, 0.4, 2.0, 4.0 and 11.0 mol.%) ceramics were prepared by solid state reaction and sintering process. The lattice parameter a and unit cell volume of pure PMNT ceramic were increased with ZnO modification. The temperature of maximum dielectric constant (Tmax), the freezing temperature (Tf), the depolarization temperature (Td) and the polar ordering temperature (TP) increased while the diffuseness parameter (δ) decreased with the increase in ZnO content, indicating an enhancement of ferroelectric ordering and a decrease in a degree of relaxor behavior of PMNT ceramics by ZnO modification. Polarization-electric field hysteresis loop and butterfly-like strain-electric field curve were displayed around room temperature in the 11.0 mol.% ZnO-modified PMNT sample, which indicated an establishment of polar macro domains. Electrostrictive coefficient (M) reached a highest value of 22.22 × 10−16 m2/V2 for the PMNT/4.0 mol.%ZnO ceramic, which made it a promising material for applications as electrostrictive actuators.