Mitigating climate change represents one of the most pressing challenges of our time. The EU has set the goal of reaching climate neutrality by 2050. The transition of manufacturing organizations is essential in reaching the EU's goal, since industry accounts for circa 25% of the total final energy use and about one-fifth of EU's GHG emissions. Energy efficiency stands as one of the essential pillars of industrial decarbonization, with energy management playing a pivotal role in reaching its full potential. To remain competitive in the long term and align with the EU's carbon neutrality goal for 2050, the manufacturing industry must enhance energy efficiency in a cost-effective way. Manufacturing companies are exploring new ways of working with energy management in order to meet the requirements for both radical and incremental innovations needed to achieve the climate neutrality goal. However, due to the high complexity of industrial energy systems and its high diversity among sectors, improving energy efficiency is a difficult task. Knowledge, especially extensive knowledge, is a key factor for adopting innovations in energy efficiency and industrial processes.The aim of this thesis is to explore the role of industrial energy management in the transition toward sustainable energy systems using an extended system approach. Employing top-down and bottom-up approaches, this thesis specifically focuses on three key aspects: industrial energy management practices, knowledge dynamics in industrial energy management, and policy evaluation. Key aspects of this thesis have been studied by means of mixed methods, such as literature reviews, interviews, case study with action research approach, survey, and evaluations. This thesis advocates that energy management practices (EnMPs) include activities beyond energy efficiency improvements. Specifically, they incorporate activities related to the decarbonization of industrial processes, including energy supply (own and purchased) and fuel conversion, at the very least.The results show that internal EnMPs revolve around a focus on technologies, processes, and leadership, for which knowledge creation is an ongoing and evolving process. EnMPs encompass a comprehensive set of strategies and actions undertaken by manufacturing organizations to enhance energy efficiency, reduce greenhouse gas emissions, and navigate the transition towards sustainable energy systems. Such practices consist of the following components: energy conservation, energy efficiency, process innovation, energy supply and compensation measures. Furthermore, this iv thesis has shown that external EnMPs are connected to the participation in energy policy programs and voluntary initiatives and is a common practice in energy management work.Organizations often employ a combination of these strategies to achieve climate neutrality and align with environmental sustainability goals. Successful implementation of EnMPs is contingent upon deep process knowledge, especially in the case of radical process innovations, wh...