Systems and methods are disclosed for mobile user identification and tracking for load balancing in packet processing systems. Packet processing systems, such as network tool optimizer (NTO) systems, are configured to receive packets associated with multiple mobile users, to extract user identification information from the packets, to store identity binding information for the mobile users, to track changes in identification information for mobile users within a communication system by analyzing control information within packets for the communication system, and to forward packets to one or more tool ports associated with the packet processing system. The packet processing systems disclosed thereby allow for user packets to be identified and sent to the same load-balanced network tool, even though the user identification information changes over time within the communication system. The disclosed embodiments are useful for a wide variety of mobile and/or non-mobile communication systems and related communication protocols.