<p>Offshore foundations are crucial for supporting marine structures like wind turbines, oil platforms, and bridges. However, when constructed in areas with liquefiable soils, liquefaction often occurs when saturated soils lose strength and stiffness due to dynamic loading, such as waves, tidal action, or seismic events. This study investigates the seismic response of liquefiable offshore foundations reinforced with lattice-type cement-mixed soil countermeasure (simplified referring to as lattice walls), focusing on the effects of spacing-to-depth ratio (<i>L</i>/<i>H</i>) of lattice walls on excess pore pressure ratio, acceleration, displacement, and settlement through numerical simulations. The results demonstrate that lattice walls effectively enhance the liquefaction resistance of near-field soils, particularly in shallow layers, by suppressing pore pressure accumulation and reducing acceleration amplification. The anti-liquefaction effect diminishes with increasing depth and distance from the lattice walls. A lower <i>L</i>/<i>H</i> ratio, achieved through denser spacing or deeper embedment, significantly improves performance, with embedment depth playing a more critical role. Settlement analyses further reveal that lattice walls effectively constrain soil deformation, reduce settlement of soils enclosed by lattice walls, and enhance seismic stability. These findings provide theoretical guidance for optimizing lattice wall configurations to mitigate liquefaction risks in seismic-prone areas.</p>