In situ polymerization of 3,4-ethylenedioxythiophene (EDOT) is achieved on the surface of 2D Ti₃C₂T_x MXene without using any oxidant, resulting in improved lithium ion storage capability of Ti₃C₂T_x/poly-EDOT hybrids. A combined experimental and theoretical study revealed the mechanism of charge-transfer-induced polymerization of EDOT, which can be extended to other similar polymers.