<p>The performance of traditional liquid and mass dampers is often inadequate to significantly mitigate the vibrations of offshore platforms induced by environmental forces, primarily due to the high mass ratio requirements. The present study introduces a control mechanism by integrating an inerter system with a geometrically modified existing water storage tank. In detail, the proposed arrangement transforms an existing tank into a compliant cell-tuned liquid mass damper with an inerter (CCTLMDI). The advantage of the proposed arrangement is that it can serve dual functions, i.e. fulfil the water tank’s functional requirement and act like a tuned mass damper with amplified mass. The efficacy of the proposed CCTLMDI is demonstrated through vibration control of a realistic jacket platform subjected to wave, wind, and seismic excitations, both individually and in combination. For a depth ratio of 0.6 and an inertance ratio of 10%, the CCTLMDI achieves maximum reductions in root mean square displacement and acceleration of the platform deck by 42.51% and 62.27%, respectively. Under combined wind-wave excitation, the reductions are 43.38% and 60.54%, whilst under combined wave-seismic excitation, they reach 73.81% and 68.23%. A probabilistic performance analysis is conducted to account for the randomness of wave loading to validate its efficacy under random wave excitations. Energy-based assessments confirm a significant decrease in total input energy, enhancing fatigue resistance and overall structural resilience. The stable performance of the CCTLMDI across varying water levels indicates its strong potential for practical implementation in both offshore and onshore structures.</p>