The Government of Indonesia (GOI) has been reforming the economyambitiously by making “Making Indonesia 4.0” (BKPM, 2018). The Indonesianwater confers an unparalleled source of relative economic estimated to assistmore than USD 280 billion (World Bank, 2018). This potential will produceenhanced development, employment, food security, ecosystem protection forfuture generations, and further Indonesia's ambition to become a global"maritime nexus. In this matter Indonesia is one of the countries trying to makeeffort to boost economic cooperation through diplomacy for the benefit ofIndonesian economy in IORA Forum. This research would be conducted usingQualitative approach with the objectives to analyse Indonesia diplomacy role inIORA. The author analyse it using regime, regionalism and diplomacy conceptswith the result that the diplomacy strategy undertaken by the Government ofIndonesia to enforce economic cooperation is quite well-run. Indonesiadiplomacy has succeeded to strengthen Indonesia’s position in IORA

Keywords: Diplomacy, Regionalism, Economic Cooperation, Indian Ocean RimAssociations (IORA)