A high-performance metamaterial absorber based on 2.5-D miniaturization design is proposed in this paper, whose absorbing band covers the UHF radio frequency identification (RFID) operation band worldwide. The absorber uses metallized vias to increase electrical length and expand absorption bandwidth. Polarization difference caused by the thickness of the dielectric in this process can be reduced by adjusting resistance of the upper or lower layer separately. Size of the unit cell is miniaturized to 13.6 mm×13.6 mm, about 1/60 at the center frequency. Detailed simulation and experimental results show that the 2.5-D miniaturized high-performance metamaterial absorber has absorptivity of more than 99% among 840—960 MHz on average. Compared with the results in published literature, the 95% absorption bandwidth is increased more than 45%. Thus, the absorber can be used to improve the reliability of RFID systems in restricted spaces.