A multifunctional eutectogel (DES-AL-CNC) was prepared using alkali lignin (AL) and cellulose nanocrystals (CNC) as raw materials and deep eutectic solvent (DES) as solvent. The DES-AL-CNC eutectogels were characterized using infrared spectroscopy, scanning electron microscopy, and mass spectrometer. The results showed that the addition of AL resulted in excellent mechanical properties, adhesion and UV resistance of the eutectogel. When the addition of AL was 0.3%, the eutectogel reached the maximum strain at break and tensile strength of 852% and 542 kPa, respectively; it could easily adhere to various substrate surfaces, including the adhesion strength to glass up to 32 kPa; and UV resistance up to 100%. Due to the presence of DES, the eutectogel has excellent resistance to drying, with a mass reduction of less than 10% at 65 °C for 7 days. In addition, the eutectogel can be assembled into flexible strain sensors, broadening the application of flexible wearable electronic devices.