In this study, a co-operative regenerative braking control algorithm for the HEV with an electric booster brake was proposed and its performance was evaluated. A dynamic model for the electric booster brake system was derived to develop the electric booster brake performance simulator and its performance was investigated. In addition, a dynamic model for the 6-speed AT-based hybrid vehicle was established to develop a performance simulator, and it was combined with the electric booster brake performance simulator. Considering the electric booster structure, a strategy was proposed to distribute the braking force and regenerative braking force using the electric booster. A co-operative control algorithm was proposed, wherein the regenerative torque is cut off to ensure ride comfort and maintain the braking force during downshift for braking, and then the regenerative torque is controlled considering the electric booster brake response characteristic. The combined performance simulator was used to evaluate the performance of the electric booster brake and the co-operative control algorithm, and the results indicated that the desired braking force was maintained and that the deceleration change decreased.