A safety brake system for a trailer comprises a brake end, an actuation end and a biasing unit. The brake end comprises a brake unit adapted to be secured to a trailer and positioned to block at least one wheel of the trailer when actuated. The actuation end comprises a mount adapted to be secured to a front end of the trailer and a probe operatively supported by the mount for displacement with respect to the trailer. The probe is operatively connected to the brake unit for actuating same. The probe is displaceable between a hitching state in which the probe is adapted to contact the hitch of a vehicle, and a braking state in which the probe actuates the brake unit. The biasing unit biases the probe against the hitch of the trailer in the hitching state and toward the braking state, such that the brake unit is actuated when the hitch is separated from the trailer.