The global transition toward net-zero emissions has led to the restructuring of labor markets and an intensification of the demand for sustainability-competent business graduates. However, higher-education curricula lack an operationalized, job-competency-based framework, and this gap in knowledge is especially acute in emerging industrial economies that are facing pressures due to the ongoing decarbonization of the global supply chain. In this context, this study addresses two interrelated gaps in the relevant research: the lack of a structured system of criteria to assess competency in sustainability that is specifically geared toward business education, and the insufficient attention that has been paid to causal interdependencies among such criteria in previously developed frameworks. The authors apply a two-stage, hybrid multiple-criteria decision-making design based on the KSAO framework, which classifies professional competency into knowledge (K), skills (S), abilities (A), and other characteristics (O). A modified Delphi method that involved 12 academic and industry experts serving as surrogate assessors of competency requirements for business and management students was first used to consolidate 142 literature-derived items into 26 initial criteria, which were then refined into 12 core competencies in sustainability, identified through cross-domain expert consensus. Following this, fuzzy Decision-Making Trial and Evaluation Laboratory (DEMATEL) was applied to analyze the structure of causal influence among the retained criteria. The results identified interdisciplinary work as the primary driving competency and integrated problem-solving as the central hub with the highest prominence, with the two factors forming a bidirectional feedback dynamic that anchored the competency system. The retention of four “other” criteria (O-dimension)—ethical values, normative orientation, empathy, and adaptive resilience—confirmed that competency concerning sustainability in business education extends beyond technical knowledge into deeper dispositional attributes. These findings provide business schools in Taiwan with a structurally grounded logic of sequencing for their curricula, as well as a reference framework for curriculum design that is aligned with the Association to Advance Collegiate Schools of Business (AACSB) Societal Impact standards. While the findings are grounded in Taiwan’s specific ESG regulatory and industrial context, only the methodological approach is offered as a reference for comparable settings; the substantive findings require cross-national verification.