Major earthquakes in the past have revealed extensive failures of pile-supported transmission tower-line systems (PSTLs), underscoring their vulnerability to earthquake damage. The topography of the ground has a significant impact on the dynamic behaviour of transmission towers. This study seeks to explore the dynamic performance of a tower foundation supported by piles resting on both level and sloping ground when exposed to earthquake loading. Dynamic analysis of pile foundations is carried out using three-dimensional finite element analysis software, PLAXIS 3D. The non-linear behaviour of the soil has been accounted for by employing the Hardening Soil model with small-strain stiffness. The non-linear behaviour of soil-pile contact was modelled using the 12-noded interface elements. Free field boundary conditions were applied to the vertical boundaries to minimise wave reflections. In the model, the maximum element size of the mesh was selected to be less than one-eighth to one-twelfth of the shortest wavelength, ensuring accuracy. Three earthquake time histories were chosen and modified based on the targeted response spectra for the site. The selected surface motions were deconvoluted into subsurface motions, and the soil-pile models’ responses were subsequently analysed. The seismic performance of the pile foundation, encompassing dynamic responses, was then assessed using the generated strong ground motions as seismic inputs. This study contributes valuable insights into the seismic response of pile foundations, addressing a knowledge gap and advancing the understanding of the dynamic assessment of soil media on level and sloping grounds.