Accordion- and sheet-like Ti3C2Tx MXene/K2Ti4O9 composites were synthesized as humidity sensing materials with enhanced relative humidity (RH) sensing property. The as-prepared K2Ti4O9 had an intertwined filiform nanostructure with a narrow width of 10–50 nm grown on the surface of Ti3C2Tx MXene. Both of the enlarged interlayer distance of Ti3C2Tx MXene and the formation of hydrophilic layered K2Ti4O9 nanowires promoted the adsorption, desorption and diffusion of water molecules throughout the porous framework. As a result, the composites showed a great promise in humidity sensing with high response and wide detection range. This work provides a promising tactic to develop Ti3C2Tx or other MXenes to construct MXene-derived high-performance humidity sensors.