Despite the enormous efforts to control the growth behavior of Li, achieving a dendrite-free Li deposition and high-energy-density have remained an inevitable challenge of Li metal batteries. Here, the conformal deposition of Li metal is reported on electroactive organic materials to achieve a high-energy-density and electrochemical longevity. To this end, Li2C8H4O4 (Li2TP), which can act as both the electrode material (providing the redox capacity) and Li host (inducing the dendrite-free Li deposition), is used as the model electroactive organic material. The Li2TP host exhibits reversible sequential lithiation/delithiation and Li deposition/stripping reactions. Consequently, a Li-free full cell constructed by the Li2TP host (without pre-charging) and a LiFePO4 cathode delivered a high areal capacity (approximate to 3.8 mAh cm-2), exceptional rate performance (<= 12 mA cm-2), and superior cyclability (80% capacity retention after 100 cycles). This electroactive organic material-based Li host strategy can provide a new perspective for the development of practical Li metal batteries. A conformal and dendrite-free deposition of lithium metal on electroactive organic materials (Li2C8H4O4) is demonstrated, which can achieve both redox capacity and lithium electrodeposition stabilization. This work provides a new design concept for electroactive Li hosts that enable practical Li metal batteries with high energy density and electrochemical longevity. image