In this paper a framework of key competencies for sustainability defined by UNESCO is used to evaluate the relevance of the CDIO Syllabus for promoting engineering education for sustainable development. The evaluation is performed in two steps. First, topics, terms and concepts in the CDIO Syllabus that corresponds to the different UNESCO key competencies are identified. The second step is a qualitative discussion where areas of strong mapping are highlighted and aspects that could be better visualized or strengthened in, or added to, the Syllabus are identified. Differences in definitions of various concepts between the CDIO Syllabus and the UNESCO key competencies and the overall relation between the two frameworks are discussed. It is concluded that the CDIO Syllabus is rather well aligned with the UNESCO framework, however several opportunities (not to say needs) for strengthening the Syllabus in relation to the key competencies are identified. The UNESCO key competencies are found to be useful instruments for scrutinizing and updating the CDIO Syllabus. Other opportunities for knowledge and methods transfer between the Education for Sustainable Development (ESD) domain and the Engineering Education domain are identified. The paper is proposed to be used as basis for updating the CDIO Syllabus into a version 3.0 for maintaining its relevance in a changing world.