The new ICSID Rules, which were subject to a five-year revision process, were implemented on 1 July 2022. This revision includes the inaugural ICSID Mediation Rules, which signifies the first mediation rules to be applicable to international investment dispute settlement. Consequently, it is of academic value to focus on the scope of application of the rules and analyse it as a starting point. The rationale for adopting the scope of application as a point of departure stems from its pivotal role as an inflection point and its capacity for subjective interpretation. This approach enables us to subsequently direct our attention to the provisions of the Rules themselves, facilitate a comparison with the previous mediation rules as established by other institutions, and undertake a thorough analysis of the concrete manifestations of the expansion of the scope of application of the new Mediation Rules. This will allow us to assess the degree of flexibility and completeness of the new Mediation Rules that have contributed to the expansion of the scope of application. In addition, three significant headwinds remain that hinder the rule’s implementation in future practice. These include the uncertainty surrounding its application, challenges in enforcing settlement agreements, and the discord between transparency and confidentiality. In order to address these challenges, it is imperative to identify and analyse specific mitigating measures that could facilitate the development of effective mediation mechanisms.