Economic Cooperation Organization (ECO) was granted Observer Status at the OTS with the decision of Council of Heads of States during the 10th Summit of the OTS held in Astana on 3 November 2023.

Hungary joined the Organization as an Observer Member during the OTS Summit held in Kyrgyzstan in 2018.

Turkmenistan joined the Organization as an Observer Member during the OTS Summit held in Türkiye in November 2021.

The Turkish Republic of Northern Cyprus became Observer Member of the Organization during the Samarkand Summit in November 2022.