The number of biogas plants in Poland is growing disproportionately slowly compared to the resource potential of agriculture and the agri-food processing industry. At the same time, livestock production struggles with managing animal waste and minimizing its environmental impact. Anaerobic digestion of animal waste in the form of slurry and manure can reduce its environmental impact while simultaneously generating renewable energy. The aim of this study was to determine the current role of slurry, manure, and poultry droppings in the mix of Polish agricultural biogas plants and their biogas potential. Statistical data on biogas production in Poland from 2011 to 2024 and the consumption of substrates from various sources, with particular emphasis on livestock manure, were analyzed. Biogas efficiency analyses were performed for five types of animal manure in a specialized laboratory. The advantages of biogas production were identified in terms of energy production, reduced air pollutant emissions, and the use of digestate from biogas plants as fertilizers. The current number of agricultural biogas plants in Poland is less than 200, and the amount of electricity they produce is approximately 1,000 GWh. Biogas plants primarily use processing waste, while only slurry plays a significant role, accounting for approximately 15% of the total substrate mass. Manure and poultry manure are of marginal importance, accounting for 3% and 0.8% of the substrate mass, respectively. Laboratory test results indicate that all types of animal manure are valuable materials for anaerobic digestion, with liquid manure playing an important role in diluting the chamber contents, and cow, pig, and poultry manure having high biogas yields of 264.37, 205.18, and 276.54 m3/Mg ODM, respectively, with biomethane content >60%. It is rational to encourage farmers to build biogas plants and micro-biogas plants and users of existing installations to use animal faces more, which will contribute to the increase in renewable energy production and improvement of the environment.