Rare-earth zirconates (REZs) have attracted attention in the field of thermal barrier materials because they are more resistant to calcium-magnesium-aluminum-silicon oxide (CMAS) corrosion than yttria stabilized zirconia (YSZ). High-entropy design of zirconates is an effective method to enhance CMAS corrosion resistance, but currently the ability of its corrosion resistance still does not meet the growing requirement. In this work, a solid-state reaction technique was used to synthesize high-entropy rare-earth zirconate (HE-REZ) (Y_0.2Gd_0.2Er_0.2Yb_0.2Lu_0.2)₂Zr₂O₇ powder with a single-phased defect fluorite structure, and pressureless sintering (PLS) combined with cold isostatic pressing (CIP) technique was used to efficiently prepare bulk samples. The phase composition, microstructure, element distribution, thermal and mechanical properties were studied, focusing on the CMAS corrosion resistance. According to the results, under the same CMAS corrosion environment at 1300 ℃, the corrosion depth of HE-REZ with a relative density of 98.6% is only 2.6% of 7YSZ and 22.6% of Gd₂Zr₂O₇ (GZO). The synergistic effect of zirconates' chemical inertness and high-entropy materials' sluggish diffusion accounts for this exceptional corrosion resistance. The obtained HE-REZ shows higher hardness and Young's modulus, larger coefficient of linear expansion, and lower thermal conductivity than ever, making its mechanical and thermal properties superior to GZO. All these outcomes demonstrate the good application potential of (Y_0.2Gd_0.2Er_0.2Yb_0.2Lu_0.2)₂Zr₂O₇ in the field of thermal barrier materials.