Environmental change includes a wide range of global and local changes, such as climate change, biodiversity loss and pollution. These changes are often the result of human activities, including industrial production, use of natural resources and energy consumption. Environmental protection refers to policies, practices and activities aimed at preserving natural resources and minimizing negative impacts on the environment. This includes efforts to reduce emissions, preserve ecosystems, promote sustainable resource management and reduce waste. An instrument of great importance and influence on the economy, making up a significant part of the GDP of many countries, including the Republic of Croatia, which can be used to act on the above, is public procurement, or an approach within it called green public procurement. It includes environmental criteria in the procurement process by which the public sector buys goods, services and works necessary for its functioning. The aim of such procedures is to reduce the impact on the environment. This may include sourcing products that are energy efficient, produced with minimal environmental damage, using recycled materials or those designed for longevity and recycling. In the context of increasing global challenges related to environmental changes, green public procurement represents a key tool for public institutions to contribute actively to sustainability and environmental protection, while promoting economic efficiency. The energy sector has a key role in the context of environmental protection, public procurement and green public procurement, especially when considering its significant impact on environmental changes through greenhouse gas emissions and high consumption of resources. By this alone we are talking about his great responsibility in environmental protection and positive action by reducing dependence on fossil fuels, increasing the share of renewable energy sources, implementing technologies to reduce emissions, etc. The development and application of green public procurement in general, as well as in the energy sector, in this paper was covered by theoretical research, while empirical research sought to determine the subjective and objective dimensions of the state and effect of the application of the instrument of green public procurement in the energy sector in Croatia so far, and these elements were evaluated by research at the level of sectoral energy clients. The results obtained from the research served as an objective basis for proposing further forms of green public procurement and opportunities implemented within the energy sector in the future.