The increasing demand for high-speed and reliable Internet of Things (IoT) connectivity presents serious challenges to existing terrestrial and satellite-based networks, such as congestion, high costs, and scalability limitations. High-altitude platforms (HAPs) are a viable alternative, providing wide-area coverage and low-cost deployment. However, they are constrained by limited radio frequency (RF) bandwidth. We propose a hybrid free-space optical (FSO)-RF communication system for HAP-enabled IoT connectivity to address this limitation. FSO can cover a dense area of IoT communications at high speed through FSO links to access points (APs). At the same time, RF can provide wide area coverage to IoT devices outside the range of APs. We analyze the system’s performance by deriving the ergodic capacity for both APs and remote IoT devices. Through Monte Carlo simulations, we validate the theoretical model, while numerical results demonstrate the system’s effectiveness in enhancing IoT connectivity.