The monopile foundation is one of the most common types of foundations widely used for offshore wind turbines. Offshore wind turbine installation in seismic regions is globally expanding, reflecting an escalating trend in offshore renewable energy infrastructure development. The seismic behavior of foundations plays a pivotal role in determining the structural integrity during earthquake events. Consequently, the seismic behavior of the foundation is an essential part that needs to be investigated. Most of the past research has predominantly focused on homogeneous soil conditions, whereas real-world scenarios often entail encountering stratified soil conditions. This paper presents a series of three-dimensional (3D) finite element (FE) analyses performed on laterally loaded monopiles embedded in a two-layer sand profile using the Mohr–Coulomb plasticity constitutive model. In this paper, a simple pseudo-static method has been employed, wherein seismic forces are converted into equivalent static horizontal and vertical forces by utilizing seismic acceleration coefficients (kv and kh). The impact of varying pile geometries (pile diameter (B) and pile length (L)), the top layer thickness of sand (d1), and seismic acceleration coefficients (kv and kh) are investigated to analyze their effect on the seismic lateral response of monopiles. A comparative analysis between the current model and findings documented in published literature has also been conducted as part of the assessment. The study reveals that the lateral capacity of monopile decreases as seismic acceleration coefficients and top layer thickness increase. However, the impact of kh is found to be more significant than that of kv. This reduction is more pronounced in monopile having smaller L/B ratio and diameter, due to their lower lateral stiffness and passive resistance.