<p>The response of under-reamed piles subjected to dynamic loading in cohesive soils is still in the early stages of development. The present analysis utilises a three-dimensional finite element-based numerical analysis to evaluate the response of under-reamed piles subjected to machine-induced vibration, considering variations in soil depth, soil strength and soil stratum, i.e. homogeneous or layered cohesive soil. Optimal geometric parameters have been determined by analysing the shaft diameter, embedment ratio, bulb-to-shaft diameter ratio, bulb angle, and bulb position. Furthermore, the performance of double bulb under-reamed piles with different bulb spacing-to-diameter ratios has been compared to single bulb configurations. Additionally, a comparative study with conventional piles (without bulbs) has also been prepared in terms of percentage amplitude reduction by varying the pile length, excitation frequency, undrained cohesion, and depth of the soil layer. Moreover, a representative figure illustrating the displacement contour plots over time for under-reamed piles subjected to cyclic loading conditions has also been presented. An additional set of figures has been provided, demonstrating the response of the piles once the machine vibration has been stopped after being active for a period of time. This study aims to advance the understanding and application of under-reamed piles in engineering practices.</p>