The Paris Agreement, adopted in 2015, is ushering in a new climate regime. Owing to the increasing importance of technology development and transfer, a technology subregime became part of the Paris Agreement in the form of Article 10, which obligates parties to strengthen their cooperative action on technology development and transfer. This technology subregime includes the Technology Mechanism as a working mechanism, established in 2010 under the United Nations Framework Convention on Climate Change (UNFCCC). The effective implementation of the technology subregime hinges upon the supporting role of the Technology Mechanism, particularly its implementing organization, the Climate Technology Centre & Network (CTCN). Technology subregimes are regarded not only as effective means to tackle environmental problems, but also as an inducement to extend the participation of developing countries in international environmental agreements. However, the means to assess them have not been widely explored. A recent UNFCCC discussion considered whether the CTCN impacted the enhancement of environmental quality in terms of mitigation of and adaptation to climate change. Therefore, this study evaluates the institutional effectiveness of the technology subregime of the Paris Agreement with the CTCN. This study utilizes five evaluation criteria: (1) environmental effectiveness, (2) technological effectiveness, (3) economic effectiveness, (4) compliance and participation incentives, and (5) administrative feasibility. It summarizes analytical results and concludes by proposing policy implications regarding the assessment of institutional effectiveness of the technology subregime.