Magnetic structure and crystal symmetry, which primarily determine the time-reversal and inversion symmetry, may give rise to numerous exotic quantum phenomena in magnetic semiconductors and semimetals when arranged in different patterns. In this work, a new layered magnetic semiconductor, Eu_3−δZn _xSn _yAs₃, was discovered and high-quality single crystals were grown using the Sn flux. According to structural characterization by x-ray diffraction and atomic-resolution scanning transmission electron microscopy, Eu_3−δZn _xSn _yAs₃ is found to crystallize in a hexagonal symmetry with the space group P6₃/ mmc (No. 194). After examining different specimens, we conclude that their stoichiometry is fixed at ∼Eu_2.6Zn_0.65Sn_0.85As₃, which meets the chemical charge balance. Eu_3−δZn _xSn _yAs₃ is composed of septuple (Eu_1−δSn _yAs₂)-Eu-(Zn _xAs)-Eu sequences. The shortest Eu–Eu distance in the system is between two Eu layers separated by Zn _xAs along the c-axis. Magnetization measurement shows an antiferromagnetic ordering in Eu_3−δZn _xSn _yAs₃ at T_N ∼ 12 K, where the magnetic easy-axis is along the c-axis, and Mössbauer spectroscopy observes magnetic hyperfine splitting on Eu and Sn at 6 K. Magnetic anisotropy is significantly different from the ones along the ab-plane in other layered Eu-based magnetic semimetals. Heat capacity measurements confirm the magnetic transition around 12 K. Electrical resistivity measurement indicates semiconductor behavior with a band gap of ∼0.86 eV. Various Eu-based magnetic semiconductors could provide a tunable platform to study potential topological and magnetic properties.