The number of green buildings has increased to address the global environmental crisis. However, green buildings face risks resulting from new materials and methods. In addition, these buildings are expected to perform at higher levels than traditional ones. The objectives of this study are to identify the possible risk factors for architects developing green building projects in South Korea and to assess risk mitigation measures. To attain this goal, fourteen risk factors and twelve mitigation measures were identified from a comprehensive literature review. A questionnaire survey was administered to architects practicing green building design. Findings revealed the ‘adoption of new technology and processes’ was the largest difference between green and traditional building projects. This study identified ‘financial risk,’ ‘design changes,’ and ‘client’s goal uncertainty’ as the top three risk factors in green building design. Additionally, the survey proposed the four most effective risk mitigation measures for green building projects: (1) ‘contract indicating each party’s roles, liabilities and limitations clearly’; (2) ‘utilizing integrated design process’; (3) ‘understanding client’s goal in green building projects’; and (4) ‘improving communication and coordination among stakeholders.’ There are a few studies focusing on the architects’ perceived risk concerning green building projects; however, this study expands the knowledge and fills the literature gap. Additionally, this study provides a comprehensive understanding of critical risks and mitigation measures that can benefit South Korea’s green building design practice through better risk management.