As of today, China’s Belt and Road Initiative (BRI) continues showing signs of its transition towards green development; whilst the Thai sustainable tourism industry is encountering substantial environmental problems of unfavourable water quality and waste management outcomes. This paper dissects how China has been transitioning into the practice of a greener BRI, as well as how Thailand has benefitted from its greener BRI partnership with China in recent years. This paper delineates the major environmental issues faced by Thailand, in order to suggest why Thailand needs to urgently and responsively address any notable environmental concern for long-term economic growth and sustainability. There is a lack, if not an absence, of existing studies that analyse Sino-Thai green BRI partnerships with the presentation of supporting, updated data and statistics. The findings presented in this paper respond to such a research gap. This paper concludes by arguing that should China’s distribution of development finance to Thailand be able to enhance the latter’s environmental health and landscape, more Southeast Asian (SEA) and global emerging powers may develop an increasing interest in forming or strengthening green BRI partnerships with China. In the long run, such an optimistic outcome allows China’s diplomatic influence to grow further. China’s greener development finance plan is an ambitious, globally impactful strategy. Such an ambitious strategy aims to capitalise on the opportunities to address countries’ developmental and environmental needs to boost China’s global competence and image, in addition to elevating its diplomatic influence.