Frequent severe flood occurrences in Rathnapura city, Sri Lanka cause damages to both human lives and infrastructures. The existing flood mapping models have certain shortcomings that could be enhanced by utilizing more advanced and combined approaches. In this research, we suggested a new technique to enhance the prediction accuracy of flood susceptibility mapping by integrating the bivariate index of entropy (IoE) and support vector machine (SVM) as an ensemble method. The suggested approach was developed using four SVM kernels; polynomial , linear , sigmoid and radial basis function to examine the robustness of predictability of SVM technique. First a flood inventory map with 445 flood locations was created using satellite images, field survey and documentary sources. A spatial database was created with eight flood conditioning factors(FCFs) including altitude, slope, aspect, topographic roughness index(TRI), soil, Land use, distance from river and rainfall. Initially, IoE was utilized to assess the correlation between the various flood conditioning factors and flood occurrence. Afterwards, the results of the first step were utilized to perform SVM model. Model validation was carried out using seed cell area index(SCAI) and area under curve(AUC) methods. The highest success and prediction rates of 94.82% and 95.81% and lowest SCAI values of 0.18, 0.878 for very high and high susceptibility classes were achieved by ensemble IoE-SVM(RBF) model. Out of all the methods used, lowest accuracies were obtained by the individual IoE and SVM(RBF) method. Ensemble methods, enhance flood prediction capabilities and conditioning factor evaluation resulting in a more accurate final map.