Organizations strive to achieve their sustainability objectives by promoting environmentally friendly practices in technology usage, minimizing energy consumption, reducing e-waste, and supporting the transition to a low-carbon economy. However, the exponential growth of data generation strains energy resources; it increases the carbon footprint of information technology (IT) infrastructure, highlighting the critical role of Green IT in reducing environmental impact. Data play a central part in Green IT by enabling energy-efficient operations, optimizing resource usage, and providing insights for sustainable technology practices and environmental impact reduction. To address this intersection of Green IT and data, organizations adopt strategies such as energy-efficient data storage, cloud optimization, dark data management, and knowledge management to ensure sustainable and informed decision-making. This paper applied a survey strategy and collected data from 539 participants to derive strategic knowledge management (KM) tactics for effective dark data governance and utilization. Five primary topic clusters emerged, namely security integration, decision dynamics, governance analytics, quality metrics, and knowledge sharing. The author identified four underlying themes: awareness training, decision automation, analytics policy, and quality repositories. By incorporating these strategic KM tactics for effective dark data governance and utilization into their operational and tactical plans, organizations can enhance decision-making, improve operational efficiency, mitigate risks, unlock the potential of untapped data resources, and foster sustainable innovation in alignment with their sustainability and Green IT objectives.