Disclosed are downforce feedback systems for active aerodynamic devices, methods for making/using such systems, and vehicles equipped with a closed-loop downforce feedback system to govern operation of the vehicle's active aero device(s). A feedback control system for operating an active aerodynamic device of a motor vehicle includes one or more pressure sensors for detecting fluid pressures in one or more pneumatic or hydraulic actuators for moving the active aero device. A vehicle controller receives fluid pressure signals from these sensor(s), and calculates an actual downforce value from these signal(s). The controller retrieves a calibrated downforce value from mapped vehicle downforce data stored in memory, and determines if the actual downforce value differs from the calibrated value. If so, the controller determines a target position for a target downforce value for a current vehicle operating condition, and commands the actuator(s) to move the active aero device to the target position.