Synergistic effects between hard carbons and soft carbons are proven to be helpful for improving the electrochemical performance of carbonaceous anode for potassium-ion batteries (PIBs). However, the phase separation of precursors limits the synergistic effects and improvement of electrochemical performance. Here, inspired by the esterification reaction, the precursors of two sorts of carbon are connected at the molecular level, which boosts the synergistic effects in hybrid carbon, resulting in excellent electrochemical kinetics and low charge/discharge voltage. Consequently, the hybrid carbon anode exhibited a high specific capacity of 121 mAh·g−1 at 3.2 A·g−1, a high-rate capability, and stable cycling performance. After 500 cycles at 1 A·g−1, the average capacity fading is only 0.078% per cycle.