Low-power wireless networks (LPWN) have traditionally been central to the Internet of Things (IoT) discussion. Nevertheless, as these networks grow more complex, their control architectures and protocols reveal significant limitations, particularly when dealing with multi–hop topologies and lossy channels. To tackle these challenges, there has been growing interest in adopting Software–Defined Networking (SDN), which has revolutionized data center and campus network management over the past decade by moving away from traditional vertical infrastructure. Despite its advantages, the centralized SDN model encounters substantial difficulties in the restricted settings of LPWN. The current study investigates the application of SDN concepts to dynamically and flexibly control Industrial IoT, with a focus on minimizing and managing SDN overhead. This paper presents a novel SDN architecture, Optimized SDN (OSDN), specifically designed for LPWN, along with simulated, experimental, and analytical findings. The results highlight that OSDN meets the diverse and complex traffic demands of Industrial IoT applications throughout LPWN and that challenges in integrating SDN in limited IoT networks can be successfully addressed. The key contribution of this study is enabling SDN-style programmability on highly resource-constrained IoT devices through a lightweight control protocol and overhead-reduction mechanisms, offering flexibility and control without compromising compatibility or performance.