Supported metallic nanoparticles render highly tunable physical and chemical properties to mixed-dimensionality materials in electrocatalysts. However, some supports are susceptible to being dissolved in acidic solution or are unstable in ambient air. The development of high-performance catalysts has been facing the major hurdles of the sluggish activity in alkaline solution and requesting high energy to stabilize the nanoparticles on their supports, challenging the pH-universality and the applicability of the supported metallic nanoparticles. Here, a one-step strategy is proposed to modulate the growth of Pt quantum dots (QDs) on HF-free MXene under atomic-level by a low-temperature metal–support interaction reaction. By controllable tailoring in the morphology and strain induced by terminations, Pt (111) QDs with a sub-nanoscale size of 1.15 nm are grown as 0D/1D heterostructure to overcome the restrictions of employing reduction gas and high annealing temperature. The catalyst exhibits a low overpotential of 33.3 mV for acidic solution, while 65.1 mV for alkaline solution at a specific current density of 10 mA cm−2. This study not only paves a scalable pathway to developing cost-efficient catalysts in moderate conditions, but also demonstrates an effective surface modulation strategy for 0D/1D heterostructures.