An object tracking system including a plurality of electronic devices and a server platform is provided. The server platform generates a tracking message based on received event message, and sends the tracking message to at least one of the electronic devices located within a first predetermined range corresponding to the received event message. When one of the electronic devices detects a vehicle matched with one or more vehicle features of the event message according to the received tracking message, the one of the electronic devices generates and sends a notification message to the server platform.