Both Brazil and Japan have been active in global environmental governance, have signed important multilateral environmental agreements, and both have committed to the Sustainable Development Goals (SDGs). The two countries have been historical partners in development cooperation/assistance since 1959. Starting with a broad concept of development cooperation (assistance), this study aims at assessing the contributions and impacts of this specific type of cooperative relationship between the two countries. Using a global environmental governance analytical framework, the research assesses the Japanese official development assistance (ODA) and interrogates its contribution to and impacts on environmental protection and sustainable development in Brazil. Through literature review, document analysis, and interviews, we identify development cooperation programs and projects implemented in the period of 1981–2020 and present two cases, one in the Cerrado (PRODECER) and the other in the Amazon (SAF—Tomé-Açu), to analyze how global environmental commitments guide (or not) the provision of ODA. Such analysis is relevant to understanding global trends of environmental governance at the subnational and local levels. We argue that the environmental dimension has been incorporated into ODA projects, according to global commitments. However, more must be achieved to meet global environmental challenges.