The hydrogen evolution reaction (HER) is a key process in electrochemical water splitting. To lower the cost and environmental impact of this process, it is highly motivated to develop electrocatalysts with low or no content of noble metals. Here, we report on an ingenious synthesis of hybrid Pt_xNi_1-x, electrocatalysts in the form of a nanoparticle-nanonetwork structure with very low noble metal content. The structure possesses important features such as good electrical conductivity, high surface area, strong interlinking, and substrate adhesion, which render an excellent HER activity. Specifically, the best performing Pt_0.05Ni_0.95 sample demonstrates a Tafel slope of 30 mV dec^-1 in 0.5 M H₂SO₄ and an overpotential of 20 mV at a current density of 10 mA cm^-2 with high stability. The impressive catalytic performance is further rationalized in a theoretical study, which provides insight into the mechanism on how such small platinum content can allow for close-to-optimal adsorption energies for hydrogen.