A hydrokinetic torque coupling device includes an impeller, a casing having a first engagement surface, a turbine-piston hydrodynamically drivable by the impeller, and a biasing device. The turbine-piston is hydrodynamically drivable by the impeller and includes a turbine-piston shell having a second engagement surface facing the first engagement surface. The turbine-piston is axially displaceable relative to the impeller between a hydrodynamic transmission mode and a lockup mode. The biasing device is configured to exert an axial load against the turbine-piston to urge the turbine-piston axially away from the lockup mode and towards the hydrodynamic transmission mode. The axial load exerted by the biasing device decreases as the turbine-piston moves axially towards the lockup mode and increases as the turbine-piston moves axially away from the lockup mode.