This paper presents an efficient fragility analysis procedure for offshore structure subjected to extreme wave loading considering parameter uncertainty. Since, conventional full Monte Carlo Simulation (MCS) based fragility analysis approach would require tremendous computational time, response surface method (RSM) based metamodelling strategy has been explored for fragility analysis. Apprehending the possible error inclusion by conventional least squares method, a comparatively newer Moving Least Squares Method (MLSM) has been adopted in the RSM. By applying MLSM based RSM, module of nonlinear response analysis of the structure using finite element software can be decoupled from the main MCS loop of fragility analysis and the fragility analysis can be performed over the generated MLSM expressions for response. The wave force time history has been generated using Spectral Representation Method based on Pierson-Moskowitz Spectra. There are studies dealing with metamodelling based fragility analysis of structure under random seismic and wind load in recent years. However, paper on fragility analysis of offshore structure by MLSM has not yet been observed in the existing literature. This builds the scope of the present research. The efficiency of the procedure is illustrated by considering a three storied jacket platform structure. The results show that the present MLSM based approach yields fragility analysis results in close conformity to the most accurate full MCS approach, but in substantially lesser computational time.