System and method for completeness of transmission control protocol (TCP) high availability (HA) are disclosed. The system includes an active processor, having an application and a TCP, and a standby processor, having another application and another TCP; wherein communications among the active application, the active TCP, the standby application and the standby TCP quickly and efficiently enable the system seamlessly switching over from the active processor to the standby processor for transmission of incoming TCP data streams and outgoing TCP data streams if the active processor fails.