A portable door locking system includes a door that is hingedly positioned in a door jamb and the door includes a hinge. A locking unit is provided and the locking unit is selectively coupled to the hinge. The locking unit extends laterally between the door and the door jamb. In this way the door abuts the locking unit when the door is urged into an open position. The locking unit inhibits the door from being opened to inhibit an intruder from entering the room.