This study explores the innovative reuse of apple pomace, an agricultural byproduct from juice production, as a substrate to enhance mushroom cultivation, specifically for Pleurotus ostreatus (oyster mushrooms). Through this approach, the research aims to boost sustainability in agriculture by turning waste into a productive resource, thus reducing environmental pollution and supporting a circular economy model. The thesis examines the nutrient-rich composition of apple pomace, especially its carbon and protein content, as an ideal medium for mycelium growth. Experimentation was conducted in the Food Science Laboratory at the University of Debrecen, testing various concentrations of apple pomace in agar mediums, which revealed that lower concentrations (200 g/L) fostered higher mycelial growth. This research provides insights into optimizing mushroom yield using apple pomace while addressing potential risks like contamination from pesticides or heavy metals.