In this paper, an efficient numerical technique is applied to provide the approximate solution of nonlinear stochastic Itˆo-Volterra integral equations driven by fractional Brownian motion with Hurst parameter H. The proposed method is based on the operational matrices of modification of hat functions (MHFs) and the collocation method. In this approach, by approximating functions that appear in the integral equation by MHFs and using Newton’s-Cotes points, nonlinear integral equation is transformed to nonlinear system of algebraic equations. This nonlinear system is solved by using Newton’s numerical method and the approximate solution of integral equation is achieved. Some theorems related to error estimate and convergence analysis of the suggested scheme are also established. Finally, two illustrative examples are included to confirm applicability, efficiency and accuracy of the proposed method. It should be noted that this scheme can be used to solve other appropriate problems but some modifications are required.