Turkey joined NATO on 18 February 1952. On 11 June 1952, NATO authorities decided to establish an Allied land headquarters (LANDSOUTHEAST) in İzmir. The headquarters was initially commanded by a United States (US) Army officer – who had Turkish and Greek general officers as his deputies – and staffed by Turkish, Greek and US military personnel and NATO international civilians.

The actual establishment of the command occurred on 8 September 1952, when Lieutenant General Willard G. Wyman assumed command and established his headquarters at Şirinyer.

In 1954, representation was extended to French, Italian and United Kingdom military personnel. It was at this time that the headquarters moved to its newly constructed building in the Alsancak area of İzmir.

In 1966 the first major change occurred when French military personnel were withdrawn from the command followed by the Greek withdrawal in 1974. On 30 December 1977, Supreme Headquarters Allied Powers Europe (SHAPE) and Turkish military authorities announced another change in the command structure to be effective 1 July 1978; the command billet was to be filled by a Turkish four star Army General with a US Major General as his deputy. On 30 June 1978, General Sam Walker handed over the command to General Vecihi Akın as the first Turkish commander.

Construction of a new headquarters facility in Şirinyer, İzmir was completed in March 1994 and the headquarters moved in April 1994. In July 1994, German officers joined the staff. The Garrison at Şirinyer was named General Vecihi Akın Garrison in March 1996, after the first Turkish Commander. In August of 1998 Canadian officers were also assigned.

NATO’s new military command structure went into effect on 1 September 1999. Implicit in this structure was the assumption of a joint capability in the Southern Region, and the former Allied land headquarters was renamed as Joint Command SOUTHEAST. With the implementation of the new structure, Greek and Spanish personnel joined the establishment in September 1999, Dutch personnel in May 2000 and Hungarian personnel in July 2000.