Most current research focuses only on the lateral spreading and site failure mechanisms in fully liquefied sloped sites. However, the different ground responses of sloped sites with localized liquefiable soil pockets under seismic loading can significantly affect the site lateral spreading, leading to excessive ground movement. Therefore, this study investigates the seismic response of horizontal and sloped sites with localized liquefiable soil pockets using three-dimensional finite element models developed employing the program OpenSees. Pressure-dependent and pressure-independent multi-yield surface plasticity models are employed to describe the soil behavior. The models are first validated against existing centrifuge shaking table test results. The validated models are then utilized to conduct a comparative study of excess pore water pressure, acceleration, and displacements in horizontal and sloped sites with localized liquefiable soil pockets. The results indicate that: (1) site incline has a significant effect on the rate of soil liquefaction, with inclined liquefiable sites reaching liquefaction more rapidly; (2) the acceleration amplification factor in the central liquefied region of inclined sites decreased by 10.6% and 34.5% under shaking with peak ground acceleration of 0.1 g and 0.4 g, respectively; and (3) the localized liquefiable soil flows to both sides under seismic excitation, with inclined liquefiable sites exhibiting more pronounced lateral sliding.