During the Vietnam conflict, the 39th Signal Battalion performed yeoman service, being the first signal unit to arrive and the last to leave. The Battalion was reorganized and re-designated during its deployment on 15 June 1969 as Headquarters and Headquarters Company, 39th Signal Battalion. Once the fighting stopped, the Battalion supported the international peacekeeping force that monitored the troop withdrawal and prisoner exchange. On 15 March 1973, the Battalion stood down and became the last Regular Army battalion to leave South Vietnam.

During almost 11 years in Vietnam, the unit was decorated with all 17 campaign streamers of the Vietnam conflict and 5 Meritorious Unit Commendations. The Battalion colors were cased at Tan Son Nhut and escorted to West Germany where the headquarters element of the 447th Signal Battalion was reflagged as the Headquarters and Headquarters Detachment, 39th Signal Battalion.