Using hybrid composites is a sustainable and effective method of controlling soil erosion and improve soil conservation. There is an important research gap in optimizing hybrid composites for erosion control, especially in loess soils, considering factors such as composite percentage, incubation time, and slope degree. Addressing this gap is essential for application strategies and enhancing the utility of hybrid composites in soil management. This study investigates the optimization of bentonite/alginate/nanocellulose (BAN) composites using response surface methodology (RSM) to maximally reduce soil and water loss under a rainfall simulator from the loess soils of northern Iran. The morphological and chemical properties of the raw materials and composite were confirmed using instrumental methods such as FTIR, FESEM, and EDX analysis. The effects of different composite concentrations under different conditions on soil stability were evaluated by simulating rainfall and measuring runoff volume and sediment concentration. The results showed the optimal BAN composite significantly reduced runoff volume (75.3 %), soil loss (94.2 %), and sediment concentration (94.3 %) compared to the control. Optimal conditions were the percentage of composite (A): 2.98 % and the incubation time (B): 33.76 days, resulting in a soil loss of 5.10 t/ha, a sediment concentration of 43.18 g/L and a runoff volume of 3.84 L. These results underline the potential of using these composites in sustainable land management to improve soil health and agricultural productivity in erosion-prone regions.