Abstract: The relevance of the article is due to the growing political and economic influence of ASEAN, and of Cambodia as an integral part of ASEAN, on the world arena. The tension between the United States of America and the People’s Republic of China has resulted in an acceleration of the building of a sovereign association of South-East Asian States. One of the key instruments for building this sovereign association is investment policy and foreign direct investment. The object of this study is cooperation between Cambodia and other ASEAN countries. The subject of this study is the Cambodia and ASEAN cooperation in foreign direct investment. The main purpose of the study is to consider the Cambodia and ASEAN cooperation in FDI and identify key issues in Cambodia’s investment policy within ASEAN. According to this purpose, there are the following goals: to study foreign direct investment in the context of neoliberalism; to analyze investment policy of Cambodia; to estimate ASEAN investment climate; to investigate Cambodia and ASEAN investment cooperation. The scientific novelty of the study is due to the discovery of a significant imbalance in investment flows between Cambodia and other ASEAN countries, consisting in the predominance of inward investment over outward investment. Moreover, the author gave practical advice on improving the investment climate of Cambodia within ASEAN countries.