Offshore construction projects are characterized by high uncertainty, often resulting in persistent cost overruns and schedule delays. Traditional deterministic planning approaches are inadequate for capturing these uncertainties, as they fail to account for correlated risks and nonlinear interactions across project phases. This study applies probabilistic modelling through Monte Carlo simulation to integrate cost and schedule risk analysis for offshore project execution. Drawing on project documentation, expert judgment, and historical data, the analysis quantifies probabilistic outcomes at P10, P50, and P90 confidence levels, offering a more accurate representation of risk exposure compared to baseline deterministic estimates. Findings from multiple case studies show that procurement volatility, contractor mobilization challenges, and brownfield Hook-Up and Commissioning (HUC) activities are dominant contributors to project uncertainty. These risks, when modelled probabilistically, reveal significant deviations in both cost and schedule performance, with procurement fluctuations alone capable of driving cost overruns of up to 20% and delaying project completion by several months. By integrating cost–schedule risk analysis, the study demonstrates how probabilistic modelling provides actionable insights for contingency allocation, contractor evaluation, and the development of resilient execution strategies. Theoretically, the research contributes to project risk management literature by highlighting the importance of integrating cost and schedule uncertainties into a unified probabilistic approach. Practically, it offers project stakeholders evidence-based guidance for enhancing governance, improving delivery confidence, and strengthening resilience in high-risk offshore construction environments.