Society's dependence on digitalization triggers various digital threats. Therefore, the government through the Indonesian National Cyber and Crypto Agency (BSSN) builds cooperation with the International Telecommunication Union (ITU) to improve digital security in Indonesia. This research aims to explain the impact of the cooperation between the National Cyber and Crypto Agency (BSSN) and the International Telecommunication Union (ITU) in facing threats and challenges in the fast-growing digital system, based on the concepts of digital security and cyber diplomacy in international cooperation. The research method used is qualitative which explores the problem through a comparative study, by collecting data from various sources of literature in the form of books, scientific journals, articles, and official websites based on secondary data. The results showed that the results of the cooperation between the State Cyber and Crypto Agency (BSSN) and the International Telecommunications Union (ITU) had a significant impact on improving digital security defense in Indonesia, including; (a) strengthening digital security infrastructure through social, economic and political fields, (b) helping to establish digital cooperation in the pandemic era, (c) helping to increase state resilience through cyber diplomacy. Thus, this research makes an important contribution to understanding internet users, especially Indonesian people, to be wiser in social media.