Effective management of dairy cattle waste is crucial for the dairy industry due to its significant environmental impacts. These include greenhouse gas emissions such as methane and nitrous oxide, nutrient runoff, and ammonia volatilization, contributing to global warming, eutrophication, and acidification. Poor waste management also threatens soil and water quality, posing risks to ecosystems and public health. This study applied Life Cycle Assessment (LCA) to evaluate the environmental impacts of dairy waste management on a farm in central Portugal, focusing on manure storage and direct application as fertilizer. The reference flow considered one ton of manure transported from storage and spread onto cultivated pastures using a manure spreader. The ReCiPe 2016 method was employed to assess impacts on human health, ecosystems, and resources. The results highlighted liquid manure storage as the largest contributor to global warming, with emissions of 107.73 kg CO2 eq. Avoiding inorganic nitrogen fertilizers reduced up to 150.73 kg 1,4-Dichlorobenzene in terrestrial ecotoxicity. At the endpoint level, storage of liquid and solid manure accounted for 0.015 and 0.013 hab.eq. in human health damage, respectively, while soil application contributed the remaining impacts. The use of organic fertilizers mitigated health harm by 0.005 hab.eq. The study provides practical recommendations for dairy farmers and policymakers to enhance the sustainability of waste management, promoting strategies to reduce environmental footprints. Future research will explore alternatives such as anaerobic digestion and composting under varying conditions, stressing the importance of policy incentives, better emissions monitoring, and farmer education to foster sustainable manure management practices.