China has re-emerged to become a dominant foreign player in Cambodia. Politically, Cambodia is one of China’s oldest and closest allies. Economically, China is Cambodia’s top foreign investor, a major donor, and an increasingly important trading partner. Culturally, Chinese values are deeply embedded in many aspects of Cambodian society. However, China’s dominance is surrounded by renewed controversies. While the government warmly welcomes Chinese aid, saying that it comes with no strings attached, many experts are concerned that China is providing aid for more nefarious reasons. Critics also accuse Chinese investment and aid of having exacerbated corruption, weakened governance and harmed human rights, and of ruining Cambodia’s natural resources and environment. With such controversies, it is relevant and significant to assess the roles that China has played and continues to play in Cambodia’s socio-economic development. Using expert interviews, media analysis and an extensive literature review, this paper uniquely contributes to the existing discussion on China–Cambodia relations by closely examining the controversies of China’s investment and aid, critically analysing China’s interests in Cambodia, and asking if the relationship between the two nations is a positive-sum game.