Analysis and design of inflatable structures made of fibre reinforced composites have been the focus of many researchers in recent times. As with most designs, sources of uncertainty, variability and bias in the performance of the designed structures exist and should normally be assessed. This paper thus, seeks to identify and quantify levels of uncertainties that are in the design of a typical inflatable fender barrier structure against impact loadings and conducts reliability-based evaluation toward understanding safety levels and factors of safety to be employed for its design and for similar structures. Using a previously validated 3D parametric fluid-structure interaction analysis results of the model, implicit limit state response surface-based performance functions were derived for the structural responses to loads for the complex stresses and strain modes of failures. The First Order Reliability Method (FORM) was used to evaluate the influence of the uncertainties in materials and load parameters and hence the safety margins for the modes of failures considered. The findings in this study will provide benchmark levels for practicing engineers in carrying out optimal design of similar inflatable structures with acceptable safety levels.