<p>The growing demand for disposable cleaning wipes, the environmental concerns associated with their disposal, and the petroleum-based nature of nonwoven substrates necessitate the development of biodegradable, flushable, high-performance alternatives. A novel approach was taken in this study to prepare eco-friendly, flushable, nonwoven cellulose nanofibril (CNF)- reinforced polyvinyl alcohol (PVA) composite substrates for wet wipe applications. These substrates were made using a simple freeze-drying technique with varying proportions of CNFs and PVA. The influence of CNF content on the substrate’s microstructure and properties was studied using a range of tests, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), water absorption, alcohol retention, tensile strength, and flushability test. SEM results showed that the substrates had a porous structure, and the pore size increased with increasing CNF content. All substrates had excellent alcohol retention properties compared to commercial wipes. The addition of CNFs improved water absorption, flushability, thermal stability, and alcohol retention properties. At 40 wt.% CNF content or above, the substrates had water absorption capacities equal to or higher than those of commercial substrates. The tensile strength and modulus decreased when CNFs were added up to 30 wt.%, but these attributes improved when the CNF level reached 40 wt.% or above. The tensile strength decreased significantly when the substrates were saturated with water, with the drop more pronounced as the CNF content increased. The composite substrates exhibited self-healing properties, albeit with reduced tensile strength compared to the uncut samples. Substrates with 50 wt.% CNFs or more were fully flushable. Overall, the CNF/PVA composite substrates developed in this study exhibit numerous remarkable properties and hold great potential as an alternative to conventional wet wipes.</p>