Herein, we demonstrate the synthesis and electrochemical performance of MAX phase (Ti2AlC) derived C-K2Ti4O9 nanocomposites by one-step KOH assisted hydrothermal treatment. The MAX phase derived C-K2Ti4O9 nanocomposites was measured around 2 μm × 200 nm (length × wide) in micrometer scale and presented layered-structure obviously. Potassium titanate and disordered carbon are attained during the transition state of Ti2CTx MXene. With the help of intermediate product, the Ti2AlC can be converted to potassium titanate thoroughly. Due to the layered structure of potassium titanate and disordered carbon, the composites exhibit excellent electrochemical properties as anode materials in lithium-ion batteries (LIBs). The C-K2Ti4O9 delivered high reversible capacity of 314 mAh g−1 at 100 mA g−1 and superior rate performance.