The high penetration of renewable energy poses severe challenges to distribution network voltage stability. Hydrogen energy, with advantages such as high density, zero carbon emissions, and high calorific value, can serve as a new voltage regulation resource and actively participate in voltage control, thereby effectively enhancing system voltage resilience. Accordingly, a leader-follower (Stackelberg) game-based voltage control strategy for distribution networks assisted by power-to-hydrogen (P2H) is proposed. First, a bilevel game optimization model incorporating P2H participation is established considering the conflicting interests among the distribution system operator, the P2H operator, and the energy storage operator. With the distribution system operator acting as the leader and minimizing operating costs as the objective, electricity price subsidies are designed to guide the P2H and energy storage operators to adjust their electricity consumption behaviors, thereby ensuring voltage stability of the distribution network. Second, to account for source-load uncertainties in practical operation, an intra-day stochastic optimization algorithm using Latin hypercube sampling is developed. Finally, case study results show that the proposed model can effectively improve voltage stability in the distribution network. Moreover, the total operating cost of the distribution system operator is reduced by 14.56% and 5.67% compared to the scenarios without P2H and without an incentive mechanism, respectively.