Electrohydraulic dynamic braking system comprising a brake servo unit with electric motor actuating a master cylinder linked to the wheel brakes through an ESP module, and comprising a high-pressure accumulator linked to the tandem master cylinder, in which - the high-pressure accumulator is linked to the primary chamber of the master cylinder and to the input of the ESP module via a solenoid valve, - a control circuit receives the braking demand signals for the brake servo unit and for the ESP module to control the solenoid valve of the high-pressure accumulator according to the chosen or imposed braking mode, - the control circuit controlling: * a phase preparatory to the braking by ensuring the filling of the high-pressure accumulator from the primary chamber by actuating the brake servo unit in the absence of action on the brake or of mechanical braking control by the ESP module and by blocking the charge of brake fluid accumulated in the high-pressure accumulator, * a dynamic braking phase broken down into two steps, ** a first actual dynamic braking step with energy harvesting by isolating the master cylinder from wheel brakes (FR1-4) and by allowing the brake servo unit to respond to the action on the brake pedal with a dynamic deceleration to a threshold speed, and ** a second mechanical braking step from the threshold speed to stoppage by linking the primary chamber only to the high-pressure accumulator and to the ESP module to supply the latter with the brake fluid under pressure from the accumulator and feed the wheel brakes (SFR1- 4) for a mechanical braking. - the high-pressure accumulator is linked to the primary chamber of the master cylinder and to the input of the ESP module via a solenoid valve, - a control circuit receives the braking demand signals for the brake servo unit and for the ESP module to control the solenoid valve of the high-pressure accumulator according to the chosen or imposed braking mode, - the control circuit controlling: * a phase preparatory to the braking by ensuring the filling of the high-pressure accumulator from the primary chamber by actuating the brake servo unit in the absence of action on the brake or of mechanical braking control by the ESP module and by blocking the charge of brake fluid accumulated in the high-pressure accumulator, * a dynamic braking phase broken down into two steps, ** a first actual dynamic braking step with energy harvesting by isolating the master cylinder from wheel brakes (FR1-4) and by allowing the brake servo unit to respond to the action on the brake pedal with a dynamic deceleration to a threshold speed, and ** a second mechanical braking step from the threshold speed to stoppage by linking the primary chamber only to the high-pressure accumulator and to the ESP module to supply the latter with the brake fluid under pressure from the accumulator and feed the wheel brakes (SFR1- 4) for a mechanical braking. * a phase preparatory to the braking by ensuring the filling of the high-pressure accumulator from the primary chamber by actuating the brake servo unit in the absence of action on the brake or of mechanical braking control by the ESP module and by blocking the charge of brake fluid accumulated in the high-pressure accumulator, * a dynamic braking phase broken down into two steps, ** a first actual dynamic braking step with energy harvesting by isolating the master cylinder from wheel brakes (FR1-4) and by allowing the brake servo unit to respond to the action on the brake pedal with a dynamic deceleration to a threshold speed, and ** a second mechanical braking step from the threshold speed to stoppage by linking the primary chamber only to the high-pressure accumulator and to the ESP module to supply the latter with the brake fluid under pressure from the accumulator and feed the wheel brakes (SFR1- 4) for a mechanical braking. ** a first actual dynamic braking step with energy harvesting by isolating the master cylinder from wheel brakes (FR1-4) and by allowing the brake servo unit to respond to the action on the brake pedal with a dynamic deceleration to a threshold speed, and ** a second mechanical braking step from the threshold speed to stoppage by linking the primary chamber only to the high-pressure accumulator and to the ESP module to supply the latter with the brake fluid under pressure from the accumulator and feed the wheel brakes (SFR1- 4) for a mechanical braking.