Developing effective bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has a pivotal role in large-scale application of hydrogen energy. Herein, a facile and scalable strategy is developed to prepare in situ supported MoS₂ coupled with CoB with Se doping on carbon cloth (MoS₂/CoB–Se/CC) via a solvothermal process and subsequent selenylation treatment. For the HER, MoS₂/CoB–Se/CC delivers the smallest overpotential (93 mV) to reach 10 mA cm⁻² compared to MoS₂/CoB/CC (158 mV), MoS₂/CC (234 mV), and CoB/CC (410 mV) in 1 M KOH, indicating that the coupling effects of MoS₂ and CoB with Se doping are responsible for boosting the catalytic performance. Impressively, the designed MoS₂/CoB–Se/CC also presents outstanding catalytic activity for the OER, with only a small overpotential of 270 mV needed to drive 10 mA cm⁻². Moreover, the developed MoS₂/CoB–Se/CC used as both anode and cathode also shows remarkable catalytic performance for overall water-splitting, with a small cell voltage of 1.58 V needed to drive 10 mA cm⁻². This work provides an efficient and promising protocol to design bifunctional electrocatalysts for overall water-splitting.