This study investigates the effects of nipa bioethanol vinasse, a distillery by-product of nipa sap on the chemical and microbiological properties of Bantay Clay Loam soil in the City of Batac, Ilocos Norte, Philippines. A pot experiment was conducted using Completely Randomized Design (CRD) with five treatments: 0%, 5%, 10%, 15%, and 20% vinasse concentrations. Each treatment was replicated three times to evaluate its influence on key soil parameters, including pH, organic matter, total nitrogen, available phosphorus, exchangeable potassium, and bacterial density. Preliminary analyses revealed that the vinasse contained low levels of nitrogen and phosphorus but moderate amounts of potassium, with a strongly acidic pH. Results showed no significant changes in soil pH, organic matter, nitrogen, or phosphorus levels following vinasse application. However, a significant increase in exchangeable potassium was observed at higher vinasse concentrations. Additionally, no inhibitory effects on bacterial colony growth were detected, suggesting that vinasse is microbiologically safe and may even support microbial activity in the soil. The study concludes that while nipa bioethanol vinasse may not significantly enhance all macronutrients, it serves as a promising organic source of potassium and poses no adverse effects on soil microbial populations. These findings contribute to the growing interest in sustainable waste-to-resource practices and support the integration of agro-industrial by-products into organic soil fertility management strategies. Further studies are recommended to assess its long-term effects, optimal application methods, and potential synergies with other organic or inorganic inputs.