<p>In this study, we propose an optimal control problem for the production-maintenance system and decoupling point, as well as inventory management under segmented market demand. Adapting to changes in demand, the production-maintenance model with a decoupling point balances maintenance schedules and production rates to maximize inventory flow. The purpose is to create the best control plans that maximize system performance and reduce expenses. The main goal is to optimize the production and maintenance rates using Pontryagin’s Minimum Principle. With a single-source inventory and multi-destination demand, where demand differs among market segments, the study starts with a production-maintenance system with a single product and then generalizes to a system with multiple products. In order to improve synchronization between production and fluctuating segment-specific demands, we consider decoupling point inventory. Our method addresses the interaction between production, maintenance, and inventory management under segmented demand conditions, offering a more thorough framework than existing models. The Runge–Kutta (RK) approach for the numerical simulations shows the effectiveness of the suggested control scheme.</p>