Layered MoS₂ has been recognized as a promising low-cost alternative to Pt-based electrocatalysts towards the hydrogen evolution reaction (HER). Intensive interest has been mainly focused on designing MoS₂ nanostructures with large amounts of active edge sites and fast charge transfer. Here we report the synthesis of vanadium and nitrogen co-doped MoS₂ on reduced graphene oxide with new defect sites on the basal/edge planes and expanded interlayer spacing, which shows remarkable catalytic merits with an extremely low overpotential of 68 mV at 10 mA cm⁻² and a Tafel slope of 41 mV dec⁻¹. Its performance is superior to most current MoS₂ electrocatalysts. In addition to the charge transfer benefits of the RGO substrate, the vanadium and nitrogen dopants trigger defect sites on the basal/edge planes, and an optimized electronic structure and expanded interlayer distance are also responsible for the enhancement in catalysis. This contribution may offer a potential way to design advanced MoS₂ catalysts by modulating the defect sites and interlayer distance for efficient electrochemical water splitting.