<p>Phase change materials are capable of undergoing phase transitions when the ambient temperature changes, presenting excellent energy storage properties. In this study, for the first time, we incorporate lignin into polyethylene glycol monomethyl ether, making the prepared phase change material less prone to liquid leakage and exhibiting excellent heat storage performance. The composite phase change material MPEG-<i>g</i>-EHL was prepared by grafting polyethylene glycol monomethyl ether (MPEG) onto lignin (EHL) skeleton carrier using the chemical grafting method with toluene-2,4-diisocyanate (TDI) as the cross-linking agent. The polarization microscopy (POM) patterns clearly reveal significant differences in crystal morphology between MPEG and MPEG-<i>g</i>-EHL. The grafting structure is confirmed by the results of FTIR and XRD analyses and the maximum grafting ratio is 85.73%. When the mass ratio of MPEG to EHL is 90:10, its enthalpy efficiency reaches its maximum value of 80.30%. At this point, its melting enthalpy value is 124.80&#xa0;J g⁻¹, and its crystallization enthalpy value is 106.04&#xa0;J g⁻¹. The composite phase change material MPEG-<i>g</i>-EHL is still thermally stable after 100 cycles of heat and cold, and it has a good latent heat energy storage property. These outstanding properties make it show broad application prospects in energy storage fields such as building energy conservation and temperature control, industrial waste heat recovery, and solar thermal storage systems.</p> Graphical abstract <p></p>