Nowadays, there has been significant interest in two-dimensional (2D) materials for thermoelectrical (TE) application due to their intrinsic high electrical conductivity and weak phonon transport ability. Since a series of novel 2D 7-atomic materials (such as the MoSi₂N₄ monolayer) have been proposed (Y. L. Hong et al., Science, 2020, 369, 670), some of them are expected to be potential TE materials. In this study, through a combination of first-principles calculations and semi-classical Boltzmann transport theory, we systemically investigate the electrical and thermal transport properties of the original 2D ZrSn₂N₄ monolayer. It is interesting to find that p-type (n-type) doped ZrSn₂N₄ has a high PF value of 3.13 (2.71) mW m⁻¹ K⁻² at 1200 K. Besides, the high phonon anharmonic scattering results in a low thermal conductivity of 3.27 (3.57) W m⁻¹ K⁻¹ for p-type (n-type) ZrSn₂N₄ at 1200 K. Consequently, the optimal ZT values for p-type (n-type) doped ZrSn₂N₄ show a moderate level of 1.15 (0.91) at 1200 K. These results suggest the great potential of the ZrSn₂N₄ monolayer as a TE material.