Non-Pt or low-Pt catalysts capable for stable generation of hydrogen via water electrolysis at an industrial level of current density are highly demanded. Construction of strong metal–support connection is beneficial to improve the performance stability of electrocatalysts. Here we employed highly defective N-doped carbon nanotubes (d-N-CNT) as the support to achieve uniform and firm anchoring of Ru clusters (~ 1.9 nm) via a thermal-shock strategy. The as-prepared Ru/d-N-CNT catalyst shows excellent catalytic activity for hydrogen evolution reaction (HER) in alkaline media and requires an overpotential (ƞ) of 12 mV at 10 mA·cm−2 and 116 mV at 200 mA·cm−2 with a Ru loading of 0.025 mg·cm−2. Impressively, Ru/d-N-CNT presents robust stability for HER at both low current density (stable for at least 1000 h at 10 mA·cm−2) and the industrial level of current density (stable for at least 100 h at 1000 mA·cm−2), remarkably outperforming commercial Pt/C and Ru/C. The highly defective nature of the N-CNT support endowed the as-prepared Ru/d-N-CNT catalyst with strong metal–support adhesion that efficiently suppressed agglomeration as well as obscission of Ru clusters. Meanwhile, the rich defects increased the surface energy of the N-CNT support and resulted in improved hydrophilicity as evidenced by the liquid contact angle measurement and the bubble evolution process, which also played an important role in stabilizing the HER performance especially at large current density.