This study examines the effect of groundwater level ( GWL ) on the seismic site response behavior of a one-layered liquefiable soil using one-dimensional nonlinear numerical analyses. The response of the liquefiable soil was analyzed with the help of DeepSoil open-source software. The calibration of the numerical model was carried out using the results of a centrifuge experiment from the literature. The outcomes of the site response analyses were discussed in terms of peak horizontal acceleration, amplification ratio, excess pore pressure ratio, shear stress-strain behavior, and maximum lateral displacement. Also, additional numerical analyses were performed to investigate relationships between input motion intensity-GWL , frequency content of earthquake motion-GWL , and layer thickness-GWL . It is shown that the seismic site response behavior of the liquefiable soil is highly affected by changes in groundwater levels. Moreover, depending on the location of the groundwater level, the seismic behavior of the liquefiable soil may also change with the increase of the input motion intensity, frequency content, and layer thickness.