A method for operating a serial-parallel hybrid powertrain of a motor vehicle has the steps of mechanically decoupling the internal combustion engine from the wheels of the motor vehicle, accelerating the motor vehicle from a first speed to a second speed by means of the second electric machine, and increasing the speed n of the internal combustion engine from a first rotational speed to a second rotational speed. Increasing the speed of the internal combustion engine from the first rotational speed to the second rotational speed always takes place as a function of the increase in the speed of the motor vehicle from the first speed to the second speed. A motor vehicle may have such a serial-parallel hybrid powertrain.