Offshore construction projects are frequently subject to considerable schedule delays and cost overruns, driven by technical complexity, environmental unpredictability, and market fluctuations. Traditional deterministic approaches often fail to capture these risks, offering limited value for decision-making in high-risk project settings. This study applies an integrated probabilistic approach by combining Schedule Risk Analysis (SRA) and Cost Risk Analysis (CRA) across three offshore case studies: (i) wellhead platform developments, (ii) a Very Low Abandonment Pressure (VLAP) project, and (iii) a brownfield Teja–Pepulut (TePu) development. Monte Carlo simulations were utilized to account for both aleatory and epistemic uncertainties, generate probabilistic estimates (P10, P50, P90), and identify key risk contributors. The findings reveal consistent discrepancies between deterministic plans and probabilistic results. Schedule outcomes at both the P50 and P90 levels were regularly exceeded, showing a systematic underestimation of schedule risks. Cost analysis also indicated increased contingency requirements, with hook-up and commissioning (HUC) activities identified as the most significant contributors. Additional cost exposure was linked to contractor performance limitations and volatile market conditions. While risk profiles varied across projects, deterministic models consistently underestimated the proper level of uncertainty. The study highlights the significance of probabilistic techniques in offshore project planning, offering practical insights into contingency allocation, contractor evaluation, and resource optimization in complex marine environments.