In this paper, a probabilistic analysis of an offshore monopile foundation embedded in a spatially varying clayey soil was performed. An efficient Kriging-based probabilistic approach using a multipoint enrichment was adopted for the analysis. The aim is to compute the failure probability against exceeding a threshold value on the monopile head rotation. The soil undrained cohesion was considered as a random field with a mean value that linearly varies with depth. The proposed probabilistic approach was shown to significantly reduce the computation time with respect to the so-called AK-MCS classical Active learning method combining Kriging and Monte Carlo Simulation (MCS) methodology. Some probabilistic numerical results are presented and discussed.