Electrochemical water splitting is quite seductive for eco-friendly hydrogen fuel energy production, however, the attainment of highly efficient, durable, and cheap catalysts for the hydrogen evolution reaction (HER) remains challenging. In this study, molybdenum oxides stabilized palladium nanoparticle catalysts (MoOx-Pd) are in situ prepared on commercial carbon cloth (CC) by the facile two-step method of dip-coating and electrochemical reduction. As a self-supported Pd-based catalyst electrode, the MoOx-Pd/CC presents a competitive Tafel slope of 45.75 mVdec−1, an ultralow overpotential of 25 mV, and extremely long cycling durability (one week) in 0.5 M H2SO4 electrolyte, superior to unmodified Pd catalysts and comparable to commercial Pt mesh electrode. On the one hand, the introduction of MoOx can inhibit the growth of Pd particles to obtain ultrafine Pd nanoparticles, thus exposing more available active sites. On the other hand, density functional theory (DFT) calculation revealed that MoOx on the surface of Pd metal can regulate the electronic structure of Pd metal and enhance its intrinsic catalytic activity of HER. This work suggests that transitional metal nanoparticles stabilized by molybdenum oxides are hopeful approaches for obtaining fruitful hydrogen-producing electrocatalysts.