This study investigates the diffusion-controlled stability of single electrolytic nanobubbles on wettability-patterned nanoelectrodes using molecular simulations. The nanoelectrodes feature hydrophobic islands as preferential nucleation sites, allowing nanobubbles to grow in a pinning mode. The simulations reveal a threshold current density that distinguishes stable from unstable nanobubbles. Below this threshold, nanobubbles grow to their equilibrium states, maintaining their nanoscopic size. Above the threshold, nanobubbles undergo unlimited growth and can detach due to buoyancy. Increasing the pinning length of nanobubbles increases their instability. The Lohse-Zhang model, extended to include gas influx at the contact line, accurately predicts the behavior of nanobubbles, including equilibrium contact angles and the threshold current density. For larger systems, continuum numerical simulations with the finite difference method and the immersed boundary method are performed, showing good agreement with the molecular simulations. The findings have implications for enhancing bubble detachment and improving the efficiency of electrolysis.This study investigates the diffusion-controlled stability of single electrolytic nanobubbles on wettability-patterned nanoelectrodes using molecular simulations. The nanoelectrodes feature hydrophobic islands as preferential nucleation sites, allowing nanobubbles to grow in a pinning mode. The simulations reveal a threshold current density that distinguishes stable from unstable nanobubbles. Below this threshold, nanobubbles grow to their equilibrium states, maintaining their nanoscopic size. Above the threshold, nanobubbles undergo unlimited growth and can detach due to buoyancy. Increasing the pinning length of nanobubbles increases their instability. The Lohse-Zhang model, extended to include gas influx at the contact line, accurately predicts the behavior of nanobubbles, including equilibrium contact angles and the threshold current density. For larger systems, continuum numerical simulations with the finite difference method and the immersed boundary method are performed, showing good agreement with the molecular simulations. The findings have implications for enhancing bubble detachment and improving the efficiency of electrolysis.