The main challenges faced by magnesium-sulfur (Mg–S) batteries are the polysulfide shuttle effect and slow kinetics of S cathode, causing the severe self-discharge behavior and rapid capacity decay. Herein, we elaborately design a MoO2-loaded activated carbon cloth (denoted as MoO2@ACC) functional interlayer to realize high-performance Mg–S batteries. The ACC possesses a remarkable adsorption effect, which can effectively mitigate the polysulfide shuttle effect and enable the Mg–S batteries with a high voltage plateau. Besides, the MoO2 can observably reduce the polarization during charge/discharge process attributed by the fast reaction kinetics due to the catalytic effect. The Mg–S battery with this MoO2@ACC interlayer achieves a high energy density and good capacity retention (80.3 %) after 100 cycles (0.5 C) and effectively mitigates the Mg–S battery's self-discharge as well. This work illustrates the significant role of the interlayer with both adsorption and catalytic functions to boost the usability of the Mg–S batteries. Display omitted •The MoO2@ACC interlayer is prepared by a simple method.•The shuttle effect of the magnesium-sulfur battery is effectively blocked.•The kinetics of the magnesium-sulfur battery is significantly improved.•The magnesium-sulfur battery exhibits a high voltage plateau and high capacity retention of 80.3% at 0.5 C.