This thesis explores how Swedish institutional investors make decisions about sustainable investments under conditions of uncertainty. Focusing on the Swedish financial sector, we conducted a qualitative study to examine the factors influencing investment decisions, including regulatory, market, and technological dynamics. The research employed semi-structured interviews with decision-makers from private equity funds, asset management firms, and family offices, capturing insights into their strategies and behaviors. Our findings reveal that Swedish institutional investors integrate sustainability impacts by embedding Environmental, Social, and Governance (ESG) criteria into their investment processes. They ensure compliance with evolving regulatory frameworks, such as the EU taxonomy, and strategically use innovative technologies to enhance sustainability. Moreover, institutional investors adopt proactive risk management and stakeholder engagement practices to navigate uncertainties. The study makes a practical contribution to the field of sustainable investment by highlighting the decision-making processes specific to the Swedish context. This not only offers valuable insights for policymakers and financial institutions aiming to promote sustainable investment practices but also underscores the significance of understanding local dynamics in shaping global sustainability efforts. The insights from this study include the need for clear regulatory guidelines, the integration of advanced technologies, and the importance of aligning investments with global sustainability goals.