A locking system and method automatically lock a mobile phone in a manner that significantly reduces or eliminates unauthorized use of a mobile phone. The system includes a key lock which must have a key connected to the lock in order to move the lock from a locked condition to an unlocked condition and a power source switch that automatically de-activates the mobile phone whenever a power source of the phone is removed from the phone. The key lock must be moved into an unlocked condition in order to manually activate the phone after it has been de-activated, and the key must also be connected to the lock in order to manually de-activate the phone after the phone has been activated.