The use of big data for disaster risk reduction has become increasingly prominent across various countries. Simultaneously, the role of open governance is essential in managing and making big data publicly accessible to effectively support disaster preparedness and response. Government agencies, private sectors, and other stakeholders derive significant benefits from open governance frameworks for risk assessment and emergency response, utilizing satellite data, remote sensing, and social media data. However, the effectiveness of open governance is influenced by variations in governance structures, technological capabilities, and types of hazards. Previous research has often focused on specific hazard types, data accessibility issues, data ownership, and other barriers that affect open governance. However, the challenges how open data innovation and big data contributing to disaster preparedness are not sufficiently explored. This chapter aims to compare and analyze various case studies from both developed and developing countries, addressing the following research questions: (1) What innovative open governance practices enhance the utilization of big data for disaster preparedness? (2) How do open data innovations improve timely accessibility of big data for disaster preparedness? (3) In what ways do innovative open governance approaches foster public participation and collaboration in disaster preparedness? Five case studies will be examined across different governance contexts. The study’s significance lies in providing an integrated approach to open governance that effectively consolidates big data from diverse sources, offering a comprehensive resource applicable to all disaster types in a unified platform.