Free running model experiments on the early detection and rudder stabilization of parametric roll in regular and irregular head waves are conducted in the towing tank of Yokohama National University. The KCS (KRISO Container Ship) containership model is used in the experiment. Parametric roll motions are observed in various ship speeds and wave lengths. The parametric roll early detection algorithm based on incremental real-time Hilbert–Huang transform (IR-HHT) technique is validated by the model experiments. Results show that the occurrence of parametric roll under different cases can be successfully detected through the detection algorithm when the roll amplitudes are still small. The rudder anti-roll control is applied for the stabilization of parametric roll in regular and irregular head waves. The rudder anti-rolling is activated when parametric roll is detected by the detection algorithm. It is found that the rudder anti-rolling can successfully stabilize parametric roll in regular and irregular head waves especially when the ship speed is high. However, the effectiveness of rudder anti-rolling is limited in severe parametric roll cases with roll amplitude larger than 25°.