A trailer coupler locking device that includes: a trailer ball body, wherein the trailer ball body is shaped as a coupling ball; a plurality of locking rods, where the plurality of locking rods define elongated members which extend from the trailer ball body; and a locking mechanism. The elongated members may be placed in either a locked position or an unlocked position. When in the unlocked position, the ball body moves freely in and out of a ball mount coupler, and when in a locked position, the ball body is locked into a ball mount coupler. The locking rods selectively extend and retract by manual operation of the locking mechanism, where the locking mechanism includes a cylinder lock that is operably connected to a rotational member and a mechanical rod actuator. The mechanical rod actuator operable connects the rotational member with each locking rod and enables each locking rod to move linearly in response to the rotary motion of the rotational member.